Sunday, November 19, 2023

πŸ’₯πŸ’₯πŸ’₯ How to model in PrePoMAX ?

You can find more detailed instructions and examples in the PrePoMax documentation1 and video tutorials1. I hope this helps you get started with PrePoMax. 😊

  • The official PrePoMax website1 has a section on documentation, where you can download the PrePoMax manual in PDF format. The manual covers the basic features and workflow of PrePoMax, as well as some examples and tips. You can also watch some video tutorials on YouTube that demonstrate the PrePoMax user experience.
  • The PrePoMax 1.3.0 manual2 is a detailed guide that explains how to use PrePoMax for various types of analysis, such as static, natural frequency, heat transfer, slip wear, etc. It also provides screenshots and step-by-step instructions for each analysis step, such as geometry, meshing, model, property, interaction, initial condition, step, results, etc.
  • The PrePoMax user forum3 is a place where you can ask questions, share your experience, and get help from other PrePoMax users and developers. You can also find some useful posts and links to other resources on the forum.
  • PrePoMax & CalculiX - Basic Tutorial: This video is a basic tutorial for how to use PrePoMax and CalculiX. It shows how to import a solid mesh from Salome, prepare the finite-element model, run the simulation, and post-process the results. It also has subtitles with brief instructions.
  • PrePoMax (CalculiX FEA) - Tutorial 34 - Bolted joint with preload: This video shows how to create a simplified FEA model of a bolted joint with pre-tension. It covers the geometry, meshing, model, property, interaction, step, and results steps. It also provides a link to download the geometry file.
  • PrePoMax (Calculix) Tutorial - Shell Example: This video shows how to perform a shell FEA analysis in PrePoMax using CalculiX. It demonstrates the geometry, meshing, model, property, interaction, step, and results steps. It also provides a link to a case description and the results of the test.

Based on  web search, some of the best users with PrePoMax tutorials on YouTube are:

  • FEAnalyst1: This user has a series of tutorials on how to use PrePoMax and CalculiX for various types of FEA analysis, such as static, natural frequency, heat transfer, slip wear, etc. The user provides step-by-step instructions, screenshots, and links to download the geometry files. The user also has a website2 where you can find more information and resources.
  • Matej BorovinΕ‘ek3: This user is the developer of PrePoMax and has a basic tutorial on how to use PrePoMax and CalculiX. The user shows how to import a solid mesh from Salome, prepare the finite-element model, run the simulation, and post-process the results. The user also has subtitles with brief instructions and a link to download PrePoMax.
  • Jakub Michalski4: This user has a playlist of videos on how to use PrePoMax and CalculiX for different types of FEA analysis, such as shell, beam, contact, etc. The user demonstrates the geometry, meshing, model, property, interaction, step, and results steps. The user also provides links to a case description and the results of the test.

Can I use PrePoMax for other solvers?

According to the PrePoMax website1, PrePoMax is designed specifically for the CalculiX solver and does not support other solvers. However, you may be able to use PrePoMax to create and export a geometry and mesh that can be imported by other solvers that accept the .inp file format. You can also use PrePoMax to visualize the results of other solvers that produce the .frd file format. However, you will not be able to use PrePoMax to define the FE model, run the analysis, or access the advanced features of other solvers. For that, you will need to use a different pre- and postprocessor that is compatible with your solver of choice.

Can I use PrePoMax on a Mac?

Unfortunately, PrePoMax is not available for Mac OS. PrePoMax is based on the Microsoft .NET Framework 4.8, which is only compatible with Windows operating systems1. You will need a Windows PC or a virtual machine to run PrePoMax. Alternatively, you can look for other pre- and postprocessors that support Mac OS and CalculiX, such as Salome-Meca2 or Gmsh3

Can I run PrePoMax on Linux?

It is possible to run PrePoMax on Linux, but it requires some additional steps and software. PrePoMax is based on the Microsoft .NET Framework 4.8, which is only compatible with Windows operating systems1. However, you can use a software called Wine2 to run Windows applications on Linux. Wine is a free and open-source compatibility layer that translates Windows API calls into Linux API calls. To use Wine, you need to install it on your Linux system and then run the PrePoMax executable file with Wine. You can find more information and instructions on how to install and use Wine on the official website2 or on the WineHQ wiki.

Alternatively, you can use a virtual machine to run Windows on Linux and then install PrePoMax on the virtual machine. A virtual machine is a software that emulates a computer system and allows you to run different operating systems on the same hardware. Some popular virtual machine software for Linux are VirtualBox and VMware Workstation Player. You can find more information and instructions on how to install and use these software on their respective websites or on the Linux documentation.

Thursday, November 16, 2023

πŸ’₯πŸ’₯πŸ’₯ Which of the machine learning software is the best for data in the form of graphs, both input and output?

The best software for machine learning with graph data, both input and output, depends on your specific needs and preferences. However, some of the software that are designed for graph machine learning or can handle graph data are:

- **Google Cloud AI Platform**: This software enables you to train your machine learning models at scale, host your trained model in the cloud, and use your model to make predictions about new data. It supports various frameworks and languages, such as TensorFlow, PyTorch, scikit-learn, and more. It also offers tools for graph analysis and visualization, such as BigQuery, Dataflow, and Data Studio¹.

- **Azure Machine Learning**: This software includes a lot of great features that enable data scientists to pull data from a wide range of sources. It also allows experts to build ML models with simple scripting and human understandable coding practices. One of the top features of the ML software is that it delivers MLOps to help organizations build, test, and deploy ML models quickly. It also supports graph data and graph neural networks through its Azure Cosmos DB and Azure Databricks services².

- **IBM Machine Learning**: This software is the combination of various products, such as IBM Watson Studio, IBM Watson Machine Learning, IBM Cloud Pak for Data, and IBM Watson Openscale. It provides a comprehensive suite of tools and services for data preparation, model development, deployment, and monitoring. It also supports various frameworks and languages, such as Python, R, TensorFlow, PyTorch, and more. It also offers graph analytics and graph neural networks through its IBM Graph and IBM SNAP ML services¹.

- **PyGeometric**: This is a Python library for deep learning on graphs. It provides various methods and models for graph machine learning, such as graph convolutional networks, graph attention networks, graph autoencoders, and more. It also supports various graph data formats, such as NetworkX, PyTorch Geometric, and DGL².

- **Deep Graph Library (DGL)**: This is another Python library for deep learning on graphs. It provides a unified interface for various graph neural network models, such as graph convolutional networks, graph attention networks, graph autoencoders, and more. It also supports various graph data formats, such as NetworkX, PyTorch Geometric, and PyGeometric².

Source:

(1) How to get started with machine learning on graphs - Medium. https://medium.com/octavian-ai/how-to-get-started-with-machine-learning-on-graphs-7f0795c83763.

(2) Introduction to Graph Machine Learning - Hugging Face. https://huggingface.co/blog/intro-graphml.

(3) Top Free Data Science and Machine Learning Platforms. https://www.g2.com/categories/data-science-and-machine-learning-platforms/free.

(4) Best Graph Plotting and Graphing Software — PlotDigitizer. https://plotdigitizer.com/graphing-software.

What is the difference between graph machine learning and traditional machine learning?

Graph machine learning and traditional machine learning are both branches of artificial intelligence that use data to generate solutions. However, they differ in the type of data they handle, the methods they use, and the problems they can solve. Here are some of the main differences between graph machine learning and traditional machine learning:

- **Data type**: Graph machine learning deals with graph data, which are data that have a network structure of nodes and edges. Graph data can represent complex and heterogeneous relationships among entities, such as social networks, molecules, knowledge graphs, and more. Traditional machine learning deals with non-graph data, which are data that have a regular or tabular structure of features and labels. Non-graph data can represent simple and homogeneous attributes of entities, such as text, images, audio, and more.

- **Methods**: Graph machine learning uses methods that can capture the topological and semantic information of graph data, such as graph signal processing, matrix factorization, random walk, and deep learning. These methods can learn from the local and global patterns of nodes and edges, as well as their attributes and types. Traditional machine learning uses methods that can capture the statistical and numerical information of non-graph data, such as regression, classification, clustering, and dimensionality reduction. These methods can learn from the frequency and distribution of features and labels, as well as their values and categories.

- **Problems**: Graph machine learning can solve problems that involve graph data or require graph representation, such as graph generation, graph evolution, graph level prediction, node property prediction, edge property prediction, and missing edge prediction. These problems can be found in various domains, such as biochemistry, computer vision, natural language processing, and recommender systems. Traditional machine learning can solve problems that involve non-graph data or require non-graph representation, such as regression, classification, clustering, anomaly detection, and sentiment analysis. These problems can be found in various domains, such as finance, marketing, healthcare, and e-commerce.

Source:

(1) Introduction to Graph Machine Learning - Hugging Face. https://huggingface.co/blog/intro-graphml.

(2) IEEE TRANSACTIONS ON ARTIFICIAL INTELLIGENCE, VOL. 00, NO. 0, 2021 1 .... https://arxiv.org/pdf/2105.00696.pdf.

(3) What is the difference between machine learning and traditional .... https://www.scribbr.co.uk/faqs/what-is-the-difference-machine-learning-and-traditional-programming/.

(4) Machine Learning vs. Traditional Programming: A Comprehensive .... https://www.cloudthat.com/resources/blog/machine-learning-vs-traditional-programming-a-comprehensive-comparison-for-optimal-use-cases.

How do I preprocess my data for graph machine learning?

Preprocessing your data for graph machine learning is an important step to ensure the quality and usability of your data. Depending on the type and source of your data, you may need to apply different techniques to prepare your data for graph machine learning. Here are some general steps that you can follow to preprocess your data for graph machine learning:

- **Collect the data**: The first step is to acquire the data that you want to use for graph machine learning. You may have your own data or use publicly available data from various sources, such as web, social media, databases, etc. You need to make sure that your data has a graph structure, which means that it consists of nodes and edges that represent entities and relationships, respectively. You also need to check the format and size of your data, and convert it to a suitable format for graph machine learning, such as NetworkX, PyTorch Geometric, DGL, etc¹².

- **Check for noisy or missing values**: The next step is to inspect your data for any errors, inconsistencies, or missing values that may affect the quality and performance of your graph machine learning model. You may need to use various methods to detect and fix these issues, such as data cleaning, data imputation, data validation, etc³⁴. For example, you may need to remove duplicate or irrelevant nodes or edges, fill in missing node or edge attributes, or validate the accuracy and completeness of your data.

- **Encode the categorical data**: Another step is to encode the categorical data in your graph, such as node or edge types, labels, or properties, into numerical values that can be used by graph machine learning algorithms. You may need to use various methods to encode the categorical data, such as one-hot encoding, label encoding, embedding, etc³⁴. For example, you may need to encode the node types of a social network graph into binary vectors, or embed the node labels of a knowledge graph into low-dimensional vectors.

- **Split the data**: The next step is to split your data into different subsets for training, validation, and testing your graph machine learning model. You may need to use various methods to split your data, such as random sampling, stratified sampling, cross-validation, etc³⁴. For example, you may need to split your data into 80% for training, 10% for validation, and 10% for testing, or use k-fold cross-validation to split your data into k equal folds and use one fold for testing and the rest for training and validation.

- **Scale the data**: Another step is to scale the data in your graph, such as node or edge features, attributes, or weights, into a standard range or distribution that can improve the performance and stability of your graph machine learning model. You may need to use various methods to scale your data, such as normalization, standardization, min-max scaling, etc³⁴. For example, you may need to scale the node features of a molecular graph into a range between 0 and 1, or standardize the edge weights of a citation graph to have zero mean and unit variance.

- **Feature engineering**: The final step is to create or select the features that can capture the relevant information and patterns of your graph data for graph machine learning. You may need to use various methods to engineer the features, such as graph signal processing, graph convolutional networks, graph attention networks, graph autoencoders, etc²⁵. For example, you may need to create node embeddings that represent the node's position and neighborhood in the graph, or select graph centrality measures that indicate the node's importance or influence in the graph.

Source: 

(1) Pre-processing - Neo4j Graph Data Science. https://neo4j.com/docs/graph-data-science/current/machine-learning/pre-processing/.

(2) Data Preprocessing Techniques in Machine Learning [6 Steps] - Scalable Path. https://www.scalablepath.com/data-science/data-preprocessing-phase.

(3) Data Preprocessing in Machine Learning: A Beginner's Guide - Simplilearn. https://www.simplilearn.com/data-preprocessing-in-machine-learning-article.

(4) Data Preprocessing in Machine Learning: 7 Easy Steps To Follow. https://www.upgrad.com/blog/data-preprocessing-in-machine-learning/.

(5) Tour of Data Preparation Techniques for Machine Learning. https://machinelearningmastery.com/data-preparation-techniques-for-machine-learning/.

What are some common graph machine learning algorithms?

Graph machine learning algorithms are methods that can learn from and make predictions on graph data, which are data that have a network structure of nodes and edges. Graph machine learning algorithms can be classified into different types based on the learning style, the input data, and the output task. Here are some common graph machine learning algorithms that you may encounter:

- **Graph signal processing algorithms**: These are algorithms that apply signal processing techniques to graph data, such as filtering, smoothing, sampling, and transforming. They can be used to extract features, enhance signals, or reduce noise from graph data. Some examples of graph signal processing algorithms are graph Fourier transform, graph wavelet transform, graph Laplacian, and graph convolution¹.

- **Graph embedding algorithms**: These are algorithms that map graph data into a low-dimensional vector space, where the nodes or edges are represented by vectors that preserve their structural and semantic information. They can be used to visualize, compare, or cluster graph data. Some examples of graph embedding algorithms are node2vec, DeepWalk, GraphSAGE, and LINE².

- **Graph neural network algorithms**: These are algorithms that use neural networks to learn from and generate graph data, such as graph convolutional networks, graph attention networks, graph autoencoders, and graph generative adversarial networks. They can be used to perform various tasks on graph data, such as node classification, link prediction, graph generation, and graph level prediction²³.

- **Graph mining algorithms**: These are algorithms that discover patterns, rules, or anomalies from graph data, such as frequent subgraphs, graph motifs, graph kernels, and graph outliers. They can be used to understand, summarize, or compress graph data. Some examples of graph mining algorithms are gSpan, gRapH, Graphlet, and LOF⁴..

Source:

(1) Introduction to Graph Machine Learning - Hugging Face. https://huggingface.co/blog/intro-graphml.

(2) 10 Machine Learning Algorithms to Know in 2023 | Coursera. https://www.coursera.org/articles/machine-learning-algorithms.

(3) Machine Learning Algorithms - GeeksforGeeks. https://www.geeksforgeeks.org/machine-learning-algorithms/.

(4) 19 Graph Algorithms You Can Use Right Now. https://memgraph.com/blog/graph-algorithms-list.

(5) en.wikipedia.org. https://en.wikipedia.org/wiki/Machine_learning.

How do I choose the right graph machine learning algorithm for my data?

Choosing the right graph machine learning algorithm for your data depends on several factors, such as the type and size of your data, the goal and complexity of your task, the available computational resources, and the desired performance and interpretability of your model. Here are some general steps that you can follow to choose the right graph machine learning algorithm for your data:

- **Understand your problem**: The first step is to define your problem clearly and identify what kind of task you want to perform on your graph data. Is it a supervised or unsupervised learning problem? Is it a classification, regression, clustering, or generation problem? Is it a node-level, edge-level, or graph-level problem? What are the inputs and outputs of your problem? What are the evaluation metrics and criteria for your problem?

- **Analyze your data**: The next step is to explore and understand your data. What is the structure and size of your graph? How many nodes and edges are there? What are the types and attributes of the nodes and edges? How dense or sparse is the graph? How homogeneous or heterogeneous is the graph? How dynamic or static is the graph? How noisy or clean is the data? How is the data distributed and labeled?

- **Evaluate the speed and training time**: Another step is to consider the speed and training time of the algorithm. How fast do you need the algorithm to run? How much time do you have to train the algorithm? How complex is the algorithm? How scalable is the algorithm? How much memory and computational power do you have? How often do you need to update the model?

- **Find out the linearity of your data**: Another step is to determine the linearity of your data. How linear or nonlinear is the relationship between the features and the target variable? How linear or nonlinear is the structure of the graph? How well can the data be separated or clustered by a linear model? How much flexibility or complexity do you need in the model?

- **Decide on the number of features and parameters**: The final step is to decide on the number of features and parameters of the algorithm. How many features do you have in your data? How many features do you need to use for your task? How many parameters do you have in your algorithm? How many parameters do you need to tune for your task? How do you select and optimize the features and parameters?

Source:

(1) Which machine learning algorithm should I use? - The SAS Data Science Blog. https://blogs.sas.com/content/subconsciousmusings/2020/12/09/machine-learning-algorithm-use/.

(2) How to Choose Right Machine Learning Algorithm? - GeeksforGeeks. https://www.geeksforgeeks.org/choosing-a-suitable-machine-learning-algorithm/.

(3) How to Choose a Machine Learning Algorithm - Label Your Data. https://labelyourdata.com/articles/how-to-choose-a-machine-learning-algorithm.

(4) An Easy Guide to Choose the Right Machine Learning Algorithm. https://www.kdnuggets.com/2020/05/guide-choose-right-machine-learning-algorithm.html.

(5) How to select the right machine learning algorithm - Telus International. https://www.telusinternational.com/insights/ai-data/article/how-to-select-the-right-machine-learning-algorithm.

What are some challenges of graph machine learning?

Graph machine learning is a branch of artificial intelligence that deals with data that have a network structure of nodes and edges, such as social networks, biological networks, knowledge graphs, and more. Graph machine learning can perform various tasks on graph data, such as classification, link prediction, generation, and analysis. However, graph machine learning also faces some challenges that make it difficult to apply and generalize to different domains and scenarios. Some of these challenges are:

- **Dynamic and evolving graphs**: Many real-world graphs are not static, but change over time due to the addition or deletion of nodes and edges, or the update of node and edge attributes. This poses a challenge for graph machine learning, as it requires the models to adapt to the temporal dynamics and capture the temporal patterns of the graph data. Moreover, some graphs may have unknown or incomplete structures, which require the models to infer or estimate the missing or latent parts of the graph¹.

- **Learning with edge signals and information**: Most graph machine learning methods focus on learning from the node features and labels, while ignoring or simplifying the edge features and labels. However, edges can also carry important information and signals that can enhance the performance and interpretability of the models. For example, edges can have different types, weights, directions, or attributes that indicate the nature and strength of the relationships between nodes. Learning with edge signals and information can help the models to better understand the graph structure and semantics¹.

- **Graph estimation**: Graph estimation is the problem of inferring or generating a graph from non-graph data, such as text, images, audio, or video. Graph estimation can be useful for transforming non-graph data into graph data, which can then be processed by graph machine learning methods. However, graph estimation is also challenging, as it requires the models to extract the relevant entities and relationships from the non-graph data, and to construct a graph that preserves the structural and semantic information of the non-graph data¹.

- **Generalization of graph models**: Generalization of graph models is the problem of applying or transferring a graph machine learning model trained on one graph to another graph that has a different structure or domain. Generalization of graph models can be beneficial for leveraging the knowledge and experience learned from one graph to another graph, especially when the target graph has limited or no labeled data. However, generalization of graph models is also challenging, as it requires the models to overcome the heterogeneity and diversity of graph data, and to adapt to the new graph characteristics and tasks¹.

Source: 

(1) Graph Deep Learning: State of the Art and Challenges. https://ieeexplore.ieee.org/document/9339909.

(2) Graph Learning: A Survey | IEEE Journals & Magazine | IEEE Xplore. https://ieeexplore.ieee.org/document/9416834.

(3) An Overview of Graph Machine Learning and Its Working - Analytics Vidhya. https://www.analyticsvidhya.com/blog/2022/10/an-overview-of-graph-machine-learning-and-its-working/.

(4) https://ieeexplore.ieee.org/servlet/opac?punumber=6287639.

(5) https://ieeexplore.ieee.org/servlet/opac?punumber=9078688.

Which software has better support for unsupervised learning on graphs?

There is no definitive answer to which software has better support for unsupervised learning on graphs, as different software may have different features, advantages, and limitations. However, based on the web search results, some of the software that are designed for unsupervised learning on graphs or can handle unsupervised learning on graphs are:

- **SUBLIME**: This is a novel framework that uses self-supervised contrastive learning and bootstrapping to optimize the graph structure without any external guidance (i.e., labels). It can generate high-quality graphs that are consistent with the original data and can be used for various downstream tasks¹.

- **PyOD**: This is a comprehensive and scalable Python library for outlier detection (anomaly detection) on graphs and other types of data. It provides various methods and models for unsupervised learning on graphs, such as graph convolutional networks, graph autoencoders, and more².

- **SimCLR**: This is a framework that uses contrastive learning to learn representations from unlabeled images. It can also be extended to graph data by using graph convolutional networks as the encoder and graph contrastive loss as the objective function³.

- **MMSelfSup**: This is an open-source toolbox and benchmark for self-supervised learning on graphs and other types of data. It provides various methods and models for unsupervised learning on graphs, such as graph convolutional networks, graph attention networks, graph autoencoders, and more⁴.

- **Anomalib**: This is an anomaly detection library that comprises state-of-the-art algorithms and features for unsupervised learning on graphs and other types of data. It provides various methods and models for unsupervised learning on graphs, such as graph convolutional networks, graph autoencoders, and more⁵.

Source: 

(1) [2201.06367] Towards Unsupervised Deep Graph Structure Learning - arXiv.org. https://arxiv.org/abs/2201.06367.

(2) Top 23 unsupervised-learning Open-Source Projects (Oct 2023) - LibHunt. https://www.libhunt.com/topic/unsupervised-learning.

(3) Top 23 unsupervised-learning Open-Source Projects (Oct 2023) - LibHunt. https://bing.com/search?q=best+software+for+unsupervised+learning+on+graphs.

(4) Introduction to Unsupervised Learning - DataCamp. https://www.datacamp.com/blog/introduction-to-unsupervised-learning.

(5) https://doi.org/10.48550/arXiv.2201.06367.

(6) https://github.com/facebookresearch/moco.

What are some applications of unsupervised learning on graphs?

Unsupervised learning on graphs is a branch of machine learning that deals with learning from graph data without any labels or supervision. Graph data are data that have a network structure of nodes and edges, such as social networks, biological networks, knowledge graphs, and more. Unsupervised learning on graphs can perform various tasks on graph data, such as clustering, visualization, dimensionality reduction, finding association rules, and anomaly detection. Some of the applications of unsupervised learning on graphs are:

- **Clustering**: Clustering is the task of grouping similar nodes or subgraphs based on their features or structures. Clustering can be used to discover communities, segments, or patterns in graph data. For example, clustering can be used to find groups of users with similar interests or behaviors in social networks, or to identify functional modules or pathways in biological networks¹².

- **Visualization**: Visualization is the task of projecting graph data into a low-dimensional space that can be easily displayed and interpreted. Visualization can be used to explore, understand, or communicate graph data. For example, visualization can be used to show the structure and properties of graph data, such as the node degree distribution, the edge weight distribution, or the node centrality measures¹².

- **Dimensionality reduction**: Dimensionality reduction is the task of reducing the number of features or dimensions of graph data while preserving the essential information or relationships. Dimensionality reduction can be used to improve the efficiency, performance, or interpretability of graph data. For example, dimensionality reduction can be used to compress or simplify graph data, or to extract latent or meaningful features from graph data¹².

- **Finding association rules**: Finding association rules is the task of discovering rules or patterns that describe the relationships or dependencies among nodes or edges in graph data. Finding association rules can be used to infer or explain graph data. For example, finding association rules can be used to discover causal or correlational relationships among nodes or edges, or to generate hypotheses or recommendations from graph data¹².

- **Anomaly detection**: Anomaly detection is the task of identifying nodes or edges that deviate from the normal or expected behavior or pattern in graph data. Anomaly detection can be used to detect or prevent graph data. For example, anomaly detection can be used to find outliers, errors, frauds, or attacks in graph data¹²⁴.

Source: 

(1) [2309.02762] Towards Unsupervised Graph Completion Learning on Graphs .... https://arxiv.org/abs/2309.02762.

(2) [2201.06367] Towards Unsupervised Deep Graph Structure Learning - arXiv.org. https://arxiv.org/abs/2201.06367.

(3) Real-world Applications of Unsupervised Learning. https://pythonistaplanet.com/applications-of-unsupervised-learning/.

(4) Unsupervised Learning with Graph Neural Networks - IPAM. https://www.ipam.ucla.edu/abstract/?tid=15546.

(5) https://doi.org/10.48550/arXiv.2309.02762.

(6) https://doi.org/10.48550/arXiv.2201.06367.

Wednesday, November 15, 2023

πŸ’₯πŸ’₯πŸ’₯ What is PrePoMAX and what is used for?

 PrePoMAX is an open-source pre and post-processor for the Calculix FEM solver¹. FEM stands for finite element method, which is a numerical technique for solving problems in engineering and physics². PrePoMAX allows you to import, mesh, define and visualize FEM features using the Calculix solver¹. It supports various CAD formats, meshing methods, feature definitions and result formats¹. You can use PrePoMAX to perform simulations of structural mechanics, heat transfer, fluid dynamics and more³. PrePoMAX is free software that you can download and modify under the terms of the GNU General Public License². PrePoMAX is developed by Dr. Matej Borovinsek from the University of Maribor in Slovenia⁴. PrePoMAX is praised for its user-friendly, modern and easy-to-use graphical interface⁴.

Source:

(1) PrePoMax - UM. https://prepomax.fs.um.si/.

(2) Downloads – PrePoMax - UM. https://prepomax.fs.um.si/downloads/.

(3) PrePoMax. Najlepszy darmowy program do analiz MES? [test]. https://polskiprzemysl.com.pl/cam-cad-cae/darmowy-program-do-analiz-mes/.

(4) http://www.dhondt.de/calculix_2.20_4win.zip.

(5) https://gitlab.com/MatejB/PrePoMax.

How do I install PrePoMAX?

To install PrePoMAX, you need to follow these steps:

- Download the latest version of PrePoMAX from the official website¹.

- Extract the zip file to a folder of your choice.

- Run the setup.exe file and follow the instructions on the screen.

- Choose the installation directory and the components you want to install.

- After the installation is complete, you can launch PrePoMAX from the Start menu or the desktop shortcut.

You can also refer to the PrePoMAX manual² for more details and troubleshooting. I hope this helps. 😊

Source: 

(1) Documentation – PrePoMax. https://prepomax.fs.um.si/documentation/.

(2) PrePoMax v1.1.0 Manual - UM. https://prepomax.fs.um.si/wp-content/uploads/2021/06/2021.06.29-PrePoMax-v1.1.0-manual.pdf.

(3) PrePoMax 1.3.0 Manual - UM. https://prepomax.fs.um.si/wp-content/uploads/2022/04/PrePoMax-v1.3.0-manual.pdf.

(4) PrePoMax 1.3.0 Manual - UM. https://prepomax.fs.um.si/wp-content/uploads/2022/04/PrePoMax-v1.3.0-manual_updated.pdf.

(5) https://staff.tu.kielce.pl/rokach/instr

What are capabilities of PrePoMAX ?

PrePoMAX is a powerful software that can help you perform various types of simulations using the Calculix FEM solver. Some of the capabilities of PrePoMAX are:

- Importing and exporting CAD geometry and mesh files in different formats¹.

- Meshing solid and shell geometries using linear and parabolic finite elements¹².

- Defining material properties, constraints, interactions, initial conditions, boundary conditions and loads for the analysis².

- Setting up different types of analysis steps, such as static, natural frequency, linear buckling, heat transfer, coupled temperature-displacement and slip wear².

- Visualizing the results using 3D scalar fields or 2D plots¹².

PrePoMAX is an open-source software that you can download and modify for free¹². It has a user-friendly, modern and easy-to-use graphical interface¹ . PrePoMAX is developed by Dr. Matej Borovinsek from the University of Maribor in Slovenia.

Source: 

(1) PrePoMax - UM. https://prepomax.fs.um.si/.

(2) PrePoMax 1.3.5 Manual - UM. https://prepomax.fs.um.si/wp-content/uploads/2022/10/PrePoMax-v1.3.5-manual.pdf.

(3)https://prepomax.discourse.group/.

Can I use PrePoMAX for fluid dynamics simulations?

PrePoMAX is mainly designed for structural mechanics and heat transfer simulations, but it can also be used for fluid dynamics simulations in some cases. According to the PrePoMAX manual², you can use PrePoMAX to set up a steady state dynamic analysis or an explicit/implicit dynamic analysis with fluid elements. However, you need to have some knowledge of the Calculix solver and the input file syntax to perform these types of analysis. PrePoMAX does not provide a graphical interface for defining fluid properties, boundary conditions and loads for fluid elements. You need to edit the input file manually or use a text editor to add these definitions. PrePoMAX can only visualize the results of fluid dynamics simulations using 2D plots, not 3D scalar fields. Therefore, PrePoMAX is not the most suitable software for fluid dynamics simulations, but it can be used as a tool to create and modify the mesh and the input file for the Calculix solver. 

Source:

(1) Features – PrePoMax - UM. https://prepomax.fs.um.si/features/.

(2) https://staff.tu.kielce.pl/rokach/instr/ppm

(3) Documentation – PrePoMax. https://prepomax.fs.um.si/documentation/.

(4) PrePoMax - UM. https://prepomax.fs.um.si/.

What is the difference between PrePoMAX and Calculix?

PrePoMAX and Calculix are two different but related software for finite element analysis. The main difference between them is that PrePoMAX is a pre and post-processor, while Calculix is a solver. This means that PrePoMAX is used to create, modify and visualize the FEM models, while Calculix is used to perform the actual calculations and simulations. PrePoMAX is based on a modern user interface that allows you to import, mesh, define and visualize FEM features using the Calculix solver¹. Calculix is a command-line based program that requires an input file with the FEM definitions and parameters². PrePoMAX can generate and edit the input file for Calculix, as well as display the results in 3D scalar fields or 2D plots¹². PrePoMAX and Calculix are both open-source software that you can download and modify for free¹²³. PrePoMAX is developed by Dr. Matej Borovinsek from the University of Maribor in Slovenia, while Calculix is developed by Guido Dhondt and Klaus Wittig from Germany¹². PrePoMAX and Calculix are compatible with each other and can be used together to perform various types of simulations, such as structural mechanics, heat transfer, fluid dynamics and more¹²³.

Source: 

(1) PrePoMax - UM. https://prepomax.fs.um.si/.

(2) Features – PrePoMax - UM. https://prepomax.fs.um.si/features/.

(3) PrePoMax v1.1.0 Manual - UM. https://prepomax.fs.um.si/wp-content/uploads/2021/06/2021.06.29-PrePoMax-v1.1.0-manual.pdf.

What are the system requirements for PrePoMAX and Calculix?

According to the PrePoMAX website¹, the system requirements for PrePoMAX are:

- Microsoft .NET Framework 4.8 or higher

- Windows 7 or higher

- 64-bit processor

- 4 GB of RAM or more

- 500 MB of disk space or more

- OpenGL 3.3 or higher compatible graphics card


The system requirements for Calculix are:

- Windows, Linux or MacOS operating system

- 64-bit processor

- 4 GB of RAM or more

- 500 MB of disk space or more

- GNU Fortran compiler or Intel Fortran compiler

PrePoMAX and Calculix are both open-source software that you can download and modify for free¹²³. PrePoMAX includes a sub-directory with the Calculix solver, so you do not need to install Calculix separately if you use PrePoMAX². However, you can also use Calculix independently or with other pre and post-processors, such as Gmsh, Salome or Paraview³.

Source: 

(1) PrePoMax - UM. https://prepomax.fs.um.si/.

(2) Downloads – PrePoMax - UM. https://prepomax.fs.um.si/downloads/.

(3) PrePoMax 1.3.0 Manual - UM. https://prepomax.fs.um.si/wp-content/uploads/2022/04/PrePoMax-v1.3.0-manual.pdf.

(4) http://www.dhondt.de/calculix_2.20_4win.zip.

(5) https://gitlab.com/MatejB/PrePoMax.

What are main advantages of PrePoMAX vs commercial software?

Some of the main advantages of PrePoMAX vs commercial software are:

- PrePoMAX is **free** and **open-source**, which means you can download and modify it without any cost or license restrictions¹².

- PrePoMAX is based on a **modern user interface** that allows you to import, mesh, define and visualize FEM features using the Calculix solver². Commercial software may have outdated or complex interfaces that require more training and expertise.

- PrePoMAX supports various **CAD formats**, **meshing methods**, **feature definitions** and **result formats** that are compatible with other open-source software, such as Open Cascade, Netgen, Gmsh, Salome and Paraview². Commercial software may have limited or proprietary formats that are not interoperable with other software.

- PrePoMAX is **user-friendly**, **easy-to-use** and **fast**. It has a simple and intuitive workflow that allows you to perform various types of simulations, such as structural mechanics, heat transfer, fluid dynamics and more². Commercial software may have more features and capabilities, but they may also be more difficult to use and slower to run.

Source: 

(1) Affordable FEA Packages for Home/Non-Commercial Use : r/fea - Reddit. https://www.reddit.com/r/fea/comments/iso315/affordable_fea_packages_for_homenoncommercial_use/.

(2) PrePoMax - UM. https://prepomax.fs.um.si/.

(3) Best open source FE : r/fea - Reddit. https://www.reddit.com/r/fea/comments/sje9q0/best_open_source_fe/.

What are the limitations of PrePoMAX?

PrePoMAX is a great software for finite element analysis, but it also has some limitations that you should be aware of. Some of the limitations of PrePoMAX are:

- PrePoMAX is mainly designed for structural mechanics and heat transfer simulations, but it can also be used for fluid dynamics simulations in some cases. However, you need to have some knowledge of the Calculix solver and the input file syntax to perform these types of analysis. PrePoMAX does not provide a graphical interface for defining fluid properties, boundary conditions and loads for fluid elements. You need to edit the input file manually or use a text editor to add these definitions. PrePoMAX can only visualize the results of fluid dynamics simulations using 2D plots, not 3D scalar fields¹.

- PrePoMAX does not support nonlinear material models, such as plasticity, creep, damage and hyperelasticity. You need to use Calculix directly or another pre and post-processor to perform simulations with these material models².

- PrePoMAX does not support contact interactions between different parts or surfaces. You need to use Calculix directly or another pre and post-processor to perform simulations with contact interactions².

- PrePoMAX does not support parallel processing or distributed computing. You need to use Calculix directly or another solver to perform simulations with multiple processors or clusters².

- PrePoMAX is still under development and may have some bugs or errors. You need to check the validity and accuracy of your results and report any issues or feedback to the developers².

Source

(1) PrePoMax v1.1.0 Manual - UM. https://prepomax.fs.um.si/wp-content/uploads/2021/06/2021.06.29-PrePoMax-v1.1.0-manual.pdf.

(2) PrePoMax - UM. https://prepomax.fs.um.si/.

BUT PREPOMAX IS STILL IN DEVELOPMENT MODE SO SOME NEW CAPABILITIES CAN EXIST IN NEXT VERSIONS OF SOFTWARE , SO FOLLOW  MATEJ AND PREPOMAX ON LINKEDIN TO BE IN TOUCH. 


Tuesday, November 14, 2023

πŸ’₯πŸ’₯πŸ’₯ How to define pressure drop on contact between two domains in Ansys Fluent?

 To define pressure drop on contact between two domains in Ansys Fluent, you need to create an interface between the two domains and specify the pressure jump across the interface. You can do this by following these steps:

  • In the Meshing mode, select the two faces that are in contact and create a Named Selection for them. Give it a meaningful name, such as “interface”.
  • In the Fluent mode, go to the Boundary Conditions panel and select the Named Selection you created. Click on Create/Edit and choose Interface from the Type drop-down menu. Click OK.
  • In the Interface panel, click on the Fluid tab and enable the Pressure Jump option. Enter the value of the pressure drop in the Pressure Jump field. You can also specify the direction of the pressure jump by choosing either Positive or Negative from the Direction drop-down menu. Click OK.

You have now defined the pressure drop on contact between two domains in Ansys Fluent. You can check the results by using the Report > Surface Integrals > Area Weighted Average > Pressure option and selecting the interface from the list. The difference between the inlet and outlet pressures should be equal to the pressure drop you specified.

For more information, you can refer to these web sources:

What is the difference between pressure drop and pressure jump?

The difference between pressure drop and pressure jump is that pressure drop is the decrease in pressure that occurs when a fluid flows through a conduit, such as a pipe, valve, or fitting, due to friction or other forces. Pressure jump is the increase or decrease in pressure that occurs when a fluid undergoes a rapid change in volume or phase, such as in a chemical reaction, phase transition, or compression/expansion process. Pressure drop is usually irreversible, meaning that the fluid loses some of its energy as heat and cannot recover its original pressure. Pressure jump is usually reversible, meaning that the fluid can regain its original pressure if the volume or phase change is reversed.

Some examples of pressure drop and pressure jump are:

  • Pressure drop: When water flows through a faucet, it experiences a pressure drop due to the resistance of the faucet and the pipe. The pressure drop depends on the flow rate, the pipe diameter, the pipe length, the pipe roughness, and the fluid viscosity. The pressure drop can be calculated using the Darcy–Weisbach equation1 or other empirical formulas2.
  • Pressure jump: When a gas is compressed in a piston, it experiences a pressure jump due to the decrease in volume. The pressure jump depends on the initial and final volumes, the initial and final temperatures, and the gas constant. The pressure jump can be calculated using the ideal gas law or other thermodynamic equations. If the piston is released, the gas can expand and return to its original pressure.
Can you explain more about reversible and irreversible processes?

Sure, I can explain more about reversible and irreversible processes. A reversible process is a theoretical concept in thermodynamics that describes a process that can be reversed without leaving any trace on the surroundings. In other words, a reversible process is one that can be undone by following the exact opposite steps, and both the system and the environment will return to their original states. For example, if you compress an ideal gas slowly and isothermally, you can reverse the process by expanding the gas slowly and isothermally, and the gas and the surroundings will have the same temperature, pressure, and entropy as before.

An irreversible process is a realistic concept in thermodynamics that describes a process that cannot be reversed without leaving some effect on the surroundings. In other words, an irreversible process is one that cannot be undone by following the exact opposite steps, and either the system or the environment or both will have different states than before. For example, if you burn a piece of paper, you cannot reverse the process by unburning the paper, and the paper and the surroundings will have different temperature, pressure, and entropy than before.

The difference between reversible and irreversible processes is related to the second law of thermodynamics, which states that the entropy of an isolated system can never decrease. A reversible process is one that does not change the entropy of the system and the surroundings, while an irreversible process is one that increases the entropy of the system and the surroundings. Therefore, all natural processes are irreversible, because they always involve some increase in entropy. A reversible process is only an idealization that helps us to calculate the maximum efficiency or work that can be obtained from a system.

How do I calculate the efficiency of a system?

There are different methods for calculating the efficiency of a system, depending on the type and purpose of the system. One common method is to use the input-output analysis, which requires measuring the inputs and outputs of a system and calculating the efficiency ratio. This method is useful for identifying the inputs required to produce the desired output, measuring the input, and comparing it with the output produced1.

The efficiency ratio can be calculated by dividing the useful output by the total input, and multiplying by 100 to get a percentage. For example, if a system uses 100 joules of energy to produce 80 joules of useful work, the efficiency ratio is (80/100) x 100 = 80%. This means that 80% of the input energy is converted into useful work, and the remaining 20% is wasted as heat, sound, or other forms of energy.

Another method is to use performance metrics, which involve measuring system performance against a set of predefined metrics, along with the input and output. This method is useful for evaluating the quality, speed, and reliability of a system, as well as the cost and resource consumption. For example, if a system produces 100 units of output per hour, using 50 units of input, and has a defect rate of 5%, the performance metrics can be used to calculate the efficiency of the system in terms of productivity, quality, and resource utilization1.

Other methods for calculating system efficiency include efficiency ratios, which compare the output of a system with a standard or benchmark output, and benchmarking, which compares the performance of a system with the best practices or industry standards1. These methods can help to identify the gaps and areas for improvement in a system, and to set realistic and achievable goals for enhancing system efficiency.

For more information, you can refer to these web sources:

Monday, November 13, 2023

πŸ’₯πŸ’₯πŸ’₯ How to create new coordinate system in Ansys Fluent?

 It seems that you want to create a new coordinate system in Ansys Fluent for your simulation. There are different ways to do that, depending on your needs and preferences. Here are some possible options:

What is the difference between a global and local coordinate system?

A global coordinate system is a fixed reference frame that describes the position and orientation of objects in a simulation or a real-world scenario. A local coordinate system is a movable reference frame that is attached to a specific object and can change its position and orientation relative to the global coordinate system. The local coordinate system is often defined according to the shape and symmetry of the object. For example, an airplane may have a local coordinate system with the x-axis aligned along the fuselage axis of the body and the y-axis pointing along the port wing1.

The difference between a global and local coordinate system is important for defining and transforming the coordinates of objects and signals in a simulation or a real-world scenario. For example, when a signal interacts with a sensor or a target, the interaction is usually specified as a function of the sensor or target local coordinates. However, when a signal propagates in the global coordinate system, the ray paths that connect transmitters, targets, and receivers are specified in global coordinates. Therefore, one needs to be able to convert local coordinates to global coordinates, and vice versa, using appropriate transformation matrices or functions23.

How to apply new coordinates to my simulation in Ansys Fluent ?

To apply new coordinates to your simulation in Ansys Fluent, you need to follow these steps:

  • First, you need to create a new coordinate system and specify its properties using the Define menu in Ansys Fluent. You can find more information and examples about this method in this forum thread1.
  • Next, you need to use the Set option in the Grid menu to select the new coordinate system as the active one for the simulation. This will affect the display of the mesh and the results in the graphics window, as well as the input and output of the boundary conditions and the reports.
  • Finally, you need to use the Transform option in the Mesh menu to apply the new coordinate system to the mesh. This will change the coordinates of the mesh nodes and the cell volumes according to the new coordinate system. You can also use this option to scale, translate, or rotate the mesh.

Alternatively, you can use a User Defined Function (UDF) in Ansys Fluent to create a new coordinate system and perform coordinate transformations for your variables. This method requires some programming skills and knowledge of the UDF syntax and structure. You can find some tips and code snippets about this method in this forum thread2.

What is the difference between scaling and rotating the mesh?

Scaling and rotating the mesh are two different ways of transforming the mesh geometry in Ansys Fluent. Scaling the mesh means changing the size of the mesh elements by a certain factor, while rotating the mesh means changing the orientation of the mesh elements by a certain angle. Both scaling and rotating the mesh can affect the accuracy and stability of the simulation, as well as the physical interpretation of the results.

Scaling the mesh can be useful for adjusting the dimensions of the mesh to match the desired units or the physical size of the problem. For example, if the mesh was created in meters, but the problem requires centimeters, scaling the mesh by a factor of 0.01 can convert the mesh units to centimeters. However, scaling the mesh can also introduce errors or distortions in the mesh quality, especially if the scaling factor is not uniform in all directions. For example, if the mesh is scaled by a factor of 2 in the x-direction, but by a factor of 0.5 in the y-direction, the mesh elements will become elongated and skewed, which can affect the numerical solution and the boundary layer resolution. Therefore, scaling the mesh should be done with caution and only when necessary.

Rotating the mesh can be useful for aligning the mesh with the desired coordinate system or the physical orientation of the problem. For example, if the mesh was created with the x-axis pointing north, but the problem requires the x-axis pointing east, rotating the mesh by 90 degrees around the z-axis can change the mesh orientation to match the problem. However, rotating the mesh can also introduce errors or inconsistencies in the mesh coordinates, especially if the rotation angle is not a multiple of 90 degrees. For example, if the mesh is rotated by 45 degrees around the z-axis, the mesh coordinates will no longer be aligned with the Cartesian axes, which can affect the input and output of the boundary conditions and the reports. Therefore, rotating the mesh should be done with care and only when necessary.

To learn more about scaling and rotating the mesh in Ansys Fluent, you can refer to the following sources:






Sunday, November 12, 2023

πŸ’₯πŸ’₯πŸ’₯ How to handle with complex geometries (models) in Ansys Fluent?

ANSYS Fluent is a powerful software for simulating fluid dynamics and heat transfer problems. It can handle complex geometries (models) by using different meshing methods and workflows. Meshing is the process of dividing the geometry into small elements that can be used for numerical calculations. Depending on the type and quality of the geometry, you may need to use different meshing tools and techniques.

One of the meshing methods available in ANSYS Fluent is the Watertight Geometry Workflow. This workflow is suitable for clean and watertight geometries, which means that there are no gaps, overlaps, or errors in the geometry. The Watertight Geometry Workflow can automatically generate a high-quality mesh for complex geometries, such as aircraft, cars, or turbines. You can also customize the mesh settings and refine the mesh in specific regions. To learn more about the Watertight Geometry Workflow, you can watch this video or take this course.

Another meshing method available in ANSYS Fluent is the Fault-Tolerant Workflow. This workflow is suitable for dirty and non-watertight geometries, which means that there are some defects or errors in the geometry. The Fault-Tolerant Workflow can wrap the geometry with a thin layer of mesh and create a fluid region without modifying the original geometry. This can save a lot of time and effort in geometry preparation and meshing. To learn more about the Fault-Tolerant Workflow, you can watch this webinar or this video.

What is Watertight Geometry Workflow?

The Watertight Geometry Workflow is a meshing method in ANSYS Fluent that can automatically generate a high-quality mesh for complex geometries, such as aircraft, cars, or turbines. The workflow guides users through a step-by-step process of simple, intuitive inputs, while behind the scenes, Fluent Meshing uses built-in intelligence and automation to create a CFD mesh using its sophisticated meshing technology. The workflow can also be customized and saved for future use. The Watertight Geometry Workflow is suitable for clean and watertight geometries, which means that there are no gaps, overlaps, or errors in the geometry. You can learn more about the Watertight Geometry Workflow by taking this course or watching this video. 😊

How do I know if my geometry is watertight?

To check if your geometry is watertight, you can use the Check Geometry tool in SpaceClaim or Fluent Meshing. This tool will detect any errors or defects in your geometry, such as gaps, overlaps, or non-manifold edges, that can prevent the geometry from being watertight. A watertight geometry is one that has no holes or leaks, and can be completely filled with fluid. You can access the Check Geometry tool by selecting the geometry in the structure tree, right-clicking, and choosing Check Geometry1. Alternatively, you can also use the Fault Detection tool in DesignModeler1. You can learn more about how to check and repair your geometry by watching this video or taking this course. 😊

Can you recommend any other tools for geometry preparation?

Sure, there are some other tools that you can use for geometry preparation in ANSYS Fluent. Here are some of them:

  • ANSYS DesignModeler: This is a CAD tool that is integrated with ANSYS Workbench and can be used to create, modify, and repair geometries for CFD analysis. You can use parametric modeling, sketching, Boolean operations, and other features to create complex geometries. You can also use the Fault Detection tool to identify and fix any errors or defects in your geometry. You can learn more about ANSYS DesignModeler by taking this course or watching this video.
  • ANSYS Meshing: This is a meshing tool that is integrated with ANSYS Workbench and can be used to generate high-quality meshes for CFD analysis. You can use different meshing methods, such as patch conforming, patch independent, cutcell, and polyhedral, to create structured, unstructured, or hybrid meshes. You can also use local sizing controls, inflation layers, and mesh quality checks to optimize your mesh. You can learn more about ANSYS Meshing by taking this course or watching this video.
  • ANSYS Fluent Meshing: This is a meshing tool that is integrated with ANSYS Fluent and can be used to generate high-quality meshes for CFD analysis. You can use different meshing workflows, such as Watertight Geometry Workflow, Fault-Tolerant Workflow, and Mosaic Meshing, to create surface and volume meshes for complex geometries. You can also use mesh adaption, mesh morphing, and mesh quality checks to improve your mesh. You can learn more about ANSYS Fluent Meshing by taking this course or watching this video.

What is the difference between ANSYS Meshing and Fluent Meshing?

ANSYS Meshing and Fluent Meshing are two different meshing tools that can be used for CFD analysis. They have some common features, such as generating 3D meshes with tet, hex, prism/wedge, and pyramid elements, and integrating with ANSYS Workbench. However, they also have some differences, such as:

  • Fluent Meshing is a strictly 3D mesher, while ANSYS Meshing can generate 2D and 3D meshes.
  • Fluent Meshing can generate meshes with conformal polyhedron elements, which can reduce cell count and improve gradient calculations, while ANSYS Meshing cannot.
  • Fluent Meshing has different meshing workflows, such as Watertight Geometry Workflow, Fault-Tolerant Workflow, and Mosaic Meshing, which can handle complex geometries with different levels of quality and automation, while ANSYS Meshing has physics-aware mesh settings that can be customized for different analysis types.
  • Fluent Meshing can handle non-conformal meshes at interfaces, which means that the mesh nodes do not have to match between adjacent cells, while ANSYS Meshing requires conformal meshes.
  • Fluent Meshing is more suitable for experienced users who want to have more control and flexibility over the meshing process, while ANSYS Meshing is more suitable for beginners or intermediate users who want to have a simpler and faster meshing process.

What is polyhedral meshing?

Polyhedral meshing is a method of generating meshes for computational fluid dynamics (CFD) analysis, where each cell is a polyhedron with multiple faces. Polyhedral meshes can have several advantages over other types of meshes, such as:

  • They can reduce the number of cells and memory requirements, while maintaining the same accuracy and resolution.
  • They can better capture the gradients and flow alignments, because of the multiple neighbors and directions of each cell.
  • They can improve the convergence and stability of the numerical solver, because of the more off-diagonal terms in the linear system.

Polyhedral meshes can be created from different sources, such as tetrahedral meshes, octree meshes, or surface meshes. There are different tools and workflows that can generate polyhedral meshes, such as ANSYS Fluent Meshing, Simcenter STAR-CCM+, or Polygon Mesh Processing. 

How do I create a polyhedral mesh in ANSYS Fluent?

To create a polyhedral mesh in ANSYS Fluent, you can use one of the following methods:

  • Converting the entire domain into polyhedral cells. This method is applicable only for meshes that contain tetrahedral and/or wedge/prism cells. To do this, you can use the Mesh/Polyhedra/Convert Domain menu in Fluent. Fluent will automatically decompose each non-hexahedral cell into multiple sub-volumes called “duals” and then agglomerate them into polyhedral cells around the original nodes. You can learn more about this method by reading the ANSYS Fluent User’s Guide1 or watching this video2.
  • Converting skewed tetrahedral cells to polyhedral cells. This method is applicable for meshes that contain some tetrahedral cells that have poor quality or skewness. To do this, you can use the Mesh/Polyhedra/Convert Skewed Cells menu in Fluent. Fluent will identify the skewed cells and convert them to polyhedral cells using the same dual decomposition and agglomeration technique as the previous method. You can learn more about this method by reading the ANSYS Fluent User’s Guide1.
  • Using the Watertight Geometry Workflow. This method is suitable for clean and watertight geometries, which means that there are no gaps, overlaps, or errors in the geometry. To do this, you can use the Fluent Meshing mode in Workbench and select the Watertight Geometry Workflow option. Fluent Meshing will guide you through a step-by-step process of simple, intuitive inputs, while behind the scenes, it will use built-in intelligence and automation to create a polyhedral mesh using its sophisticated meshing technology. You can learn more about this method by taking this course3 or watching this video4.

What is the difference between polyhedral and tetrahedral meshes?

Choosing the best meshing method for your project depends on several factors, such as:

  • The geometry and complexity of your model. Some geometries may require more refinement or special treatment to capture the flow features and boundary conditions accurately.
  • The physics and solver settings of your simulation. Some physics models, such as turbulence, heat transfer, or multiphase, may require finer or different types of meshes to ensure numerical stability and convergence.
  • The computational resources and time available for your simulation. Finer meshes usually result in more accurate solutions, but they also increase the computational cost and time of the simulation.

There is no single meshing method that works best for all cases, so you may need to try different methods and compare the results. However, some general guidelines that can help you choose a suitable meshing method are:

Popular posts