Preparing a good quality mesh is an important step for any computational fluid dynamics (CFD) or finite element analysis (FEA) simulation. A good quality mesh can improve the accuracy, stability, and efficiency of the simulation results. There are several parameters that you should control to prepare a good quality mesh, such as:
- **Cell size**: The cell size is the length of the smallest element in the mesh. A smaller cell size can capture more details of the geometry, but it also increases the computational cost and may cause numerical errors. A larger cell size can reduce the computational cost and avoid errors, but it may also introduce gaps or overlaps between elements that affect the accuracy. Therefore, you should choose an optimal cell size that balances these factors. A common rule of thumb is to use a cell size smaller than half of the gap dimension³.
- **Aspect ratio**: The aspect ratio is the ratio of a cell's longest edge to its shortest edge. A higher aspect ratio means that the cell is more elongated and has less surface area. A lower aspect ratio means that the cell is more square and has more surface area. A higher aspect ratio can improve the accuracy of some simulations, such as those involving thin features or sharp corners, but it may also cause numerical instability or divergence in others. A lower aspect ratio can improve the stability and convergence of some simulations, but it may also reduce the accuracy or introduce errors in others. Therefore, you should choose an optimal aspect ratio that suits your simulation problem and geometry.
- **Non-orthogonality**: The non-orthogonality is the angle between two adjacent cell centers and their shared faces. A higher non-orthogonality means that there is more distortion or misalignment between cells and faces. A lower non-orthogonality means that there is less distortion or misalignment between cells and faces. A higher non-orthogonality can cause numerical instability or divergence in some simulations, especially those involving complex geometries or boundary conditions. A lower non-orthogonality can improve the stability and convergence of some simulations, but it may also reduce the accuracy or introduce errors in others. Therefore, you should choose an optimal non-orthogonality level that minimizes these effects.
- **Volume ratio**: The volume ratio is the ratio of two adjacent cells' volumes. A higher volume ratio means that there is more overlap between cells and less separation between them. A lower volume ratio means that there is less overlap between cells and more separation between them. A higher volume ratio can improve the accuracy of some simulations, such as those involving thin features or sharp corners, but it may also cause numerical instability or divergence in others. A lower volume ratio can improve the stability and convergence of some simulations, but it may also reduce the accuracy or introduce errors in others. Therefore, you should choose an optimal volume ratio level that balances these factors.
These are some of the main parameters that you should control to prepare a good quality mesh for your CFD or FEA simulation. However, there are other factors that may affect your mesh quality as well, such as geometry clean-up⁵, feature removal³, duplicate face elimination³, feature edge addition³, etc., depending on your specific problem domain.
Source:
(1) 5 Tips And Tricks For A High Quality Meshing Process - Creative Fields. https://cfmesh.com/tips-tricks-for-a-high-quality-meshing-process/.
(2) What is Meshing? |Mesh Generation Overview | Cadence. https://www.cadence.com/en_US/home/explore/what-is-meshing.html.
(3) 5 Tips on How to Create a High-Quality Mesh - SimScale. https://www.simscale.com/blog/tips-high-quality-mesh/.
(4) Mesh Quality | Mesh Visualization Tips | SimScale. https://www.simscale.com/docs/simulation-setup/meshing/mesh-quality/.
(5) Guidelines for good mesh quality - FLOW-3D. https://www.flow3d.com/wp-content/uploads/2015/10/simulation-pre-check.pdf.
(6) What is Meshing? |Mesh Generation Overview | Cadence. https://www.cadence.com/en_US/home/explore/what-is-meshing.html.
Can you recommend a good open-source software for meshing?
Sure, I can recommend some good open-source software for meshing. Meshing is the process of creating a discrete representation of a geometry or domain for computational simulations, such as CFD or FEA. There are many factors that affect the quality and performance of a mesh, such as cell size, aspect ratio, non-orthogonality, volume ratio, etc. Therefore, choosing a suitable meshing software depends on your specific problem domain, geometry, and simulation requirements.
Some of the most popular and widely used open-source meshing software are:
- **MeshLab**¹: MeshLab is a system for processing and editing 3D triangular meshes. It provides a set of tools for editing, cleaning, healing, inspecting, rendering, texturing and converting meshes. It also offers features for processing raw data produced by 3D digitization tools/devices and for preparing models for 3D printing.
- **Gmsh**²: Gmsh is a 3D finite element mesh generator with a built-in CAD engine and post-processor. It allows you to create parametric models and meshes using a graphical or a command-line interface. It supports various meshing algorithms, such as Delaunay, Voronoi, structured, unstructured, hybrid, etc.
- **Salome**³: Salome is a platform for numerical simulation that integrates various components for geometry modeling, mesh generation, data visualization, and post-processing. It supports various meshing formats, such as CGNS, MED, UNV, etc. It is also python scriptable and contains some gmsh meshing algorithms.
- **MeshKit**⁴: MeshKit is a library for mesh generation that provides a collection of meshing algorithms and tools for various applications, such as reactor geometry, boundary layer, mesh sealing, mesh conversion, etc. It also supports various meshing formats, such as Exodus II, MOAB, etc.
These are some of the best open-source meshing software that I can recommend for you. However, there are other alternatives that you can explore as well, such as snappyHexMesh⁵, TetGen⁶, OpenFOAM⁷, etc. You can also check out some online resources for more information and comparison of different meshing software, such as [Meshing Tools for Open Source CFD: A Practical Point of View](^4^), [Any recommendations for an open-source meshing software please?](^2^), [Meshing Techniques and Tips], etc.
Source:
(1) MeshLab. https://www.meshlab.net/.
(2) Any recommendations for an opensource meshing software please?. https://www.reddit.com/r/CFD/comments/lo7c98/any_recommendations_for_an_opensource_meshing/.
(3) meshmixer Alternatives: 25+ 3D Modelers & Similar Apps | AlternativeTo. https://alternativeto.net/software/meshmixer/.
(4) Meshing Tools for Open Source CFD: A Practical Point of View. https://cris.vtt.fi/en/publications/meshing-tools-for-open-source-cfd-a-practical-point-of-view.
(5) MeshKit | SIGMA - Argonne National Laboratory. https://sigma.mcs.anl.gov/meshkit-library/.
(6) https://www.researchgate.net/post/What_is_the_best_meshing_code_open_source_to_use_with_OpenFoam.
(7) https://www.salome-platform.org/user-section/about/mesh.
(8) Meshing Tools for Open Source CFD: A Practical Point of View. https://cris.vtt.fi/en/publications/meshing-tools-for-open-source-cfd-a-practical-point-of-view.
(9) Any recommendations for an opensource meshing software please?. https://www.reddit.com/r/CFD/comments/lo7c98/any_recommendations_for_an_opensource_meshing/.
(10) en.wikipedia.org. https://en.wikipedia.org/wiki/MeshLab.
Can you recommend a good open-source software for CFD simulation?
Sure, I can recommend some good open-source software for CFD simulation. CFD stands for computational fluid dynamics, which is a branch of engineering and physics that uses numerical methods to analyze and solve problems involving fluid flows¹. CFD simulation can be used for various applications, such as aerodynamics, heat transfer, combustion, multiphase flows, etc.
Some of the most popular and widely used open-source CFD software are:
- **OpenFOAM**²: OpenFOAM is a free, open source software for CFD that is distributed under the General Public Licence (GPL). It is based on the finite volume method and supports various types of meshes, solvers, and models. It also has a built-in CAD engine and post-processor. OpenFOAM is suitable for complex and large-scale CFD problems and has a large and active user community.
- **SU2**³: SU2 is a free, open source software for CFD and other physics-based simulations that is distributed under the Lesser GPL (LGPL). It is based on the finite element method and supports various types of meshes, solvers, and models. It also has a Python interface and a graphical user interface. SU2 is mainly focused on aerodynamics and aerospace engineering applications and has a strong academic background.
- **Code_Saturne**⁴: Code_Saturne is a free, open source software for CFD that is distributed under the GNU GPL. It is based on the finite volume method and supports various types of meshes, solvers, and models. It also has a graphical user interface and a Python interface. Code_Saturne is developed by EDF, a French electric utility company, and is mainly used for industrial and environmental CFD problems.
These are some of the best open-source CFD software that I can recommend for you. However, there are other alternatives that you can explore as well, such as FEniCS, Nektar++, PyFR, etc. You can also check out some online resources for more information and comparison of different CFD software, such as [Open-Source CFD Software Packages: Good Enough and Free](^2^), [Simulation of Thermofluids with Open Source Tools](^3^), [CFD Software Comparison Series], etc.
Source:
(1) OpenFOAM | Free CFD Software | The OpenFOAM Foundation. https://openfoam.org/.
(2) Open-Source CFD Software Packages: Good Enough and Free. https://www.digitalengineering247.com/article/open-source-cfd-software-packages-good-enough-and-free.
(3) Simulation of Thermofluids with Open Source Tools. https://www.epc.ed.tum.de/en/tfd/lehre/simulation-of-thermofluids-with-open-source-tools/.
(4) FEATool Multiphysics - Physics Simulation Made Easy. https://www.featool.com/.
(5) Open-Source CFD Software Packages: Good Enough and Free. https://www.digitalengineering247.com/article/open-source-cfd-software-packages-good-enough-and-free.
(6) Simulation of Thermofluids with Open Source Tools. https://www.epc.ed.tum.de/en/tfd/lehre/simulation-of-thermofluids-with-open-source-tools/.
Which of these open source cfd software are most user friendly GUI ?
User-friendliness is a subjective criterion that may vary depending on the user's preferences, needs, and expectations. However, based on some general criteria, such as ease of installation, operation, customization, and support, I can try to give you some suggestions for the most user-friendly GUIs among the open source CFD software that I found in my web search.
One of the most popular and widely used open source CFD software is OpenFOAM², which is a free, open source software for CFD that is distributed under the General Public Licence (GPL). It is based on the finite volume method and supports various types of meshes, solvers, and models. It also has a built-in CAD engine and post-processor. OpenFOAM is suitable for complex and large-scale CFD problems and has a large and active user community.
However, OpenFOAM also has a steep learning curve and requires some technical skills to use it effectively. Therefore, some users may prefer to use a graphical user interface (GUI) that simplifies the interaction with the software using graphical elements instead of text files and command lines. This approach significantly reduces the learning curve enabling users to focus on problem-solving and analysis.
One of the GUIs that works natively with OpenFOAM is HELYX-OS³, which is an open-source GUI designed by ENGYS to work natively with the standard OpenFOAM libraries provided by the OpenFOAM Foundation and ESI-OpenCFD. The GUI is intended for academic use and entry-level CFD work, and it is delivered to the public under the GNU General Public License.
HELYX-OS offers a simple and intuitive interface that allows users to import geometry, create mesh, define boundary conditions, parameterize case, run simulation, compute results, post-process data with ParaView or other tools. It also provides features such as automatic mesh refinement or coarsening, parallel computing support, dynamic meshing options, etc.
Another GUI that works with OpenFOAM is SimFlow¹, which is a desktop CFD simulation software for Windows and Linux. SimFlow uses free open-source OpenFOAM libraries while also offering user-friendly GUI as a commercial CFD tool. With SimFlow you can import geometry create mesh define boundary conditions parameterize case run simulation compute results post-process data with ParaView.
SimFlow offers functionalities to handle various phenomena such as compressible flows turbulent flows heat transfer multiphase flows cavitation chemical reactions etc. It also supports various types of meshes solvers models CAD engine post-processor etc.
SimFlow has a free version that allows users to simulate up to 200'000 nodes with 2 processes in parallel or serial mode. It also has a commercial version that offers unlimited nodes processes parallel computing support dynamic meshing options etc.
These are some of the most user-friendly GUIs among the open source CFD software that I can recommend for you. However there are other alternatives that you can explore as well such as FEniCS SU2 PyFR etc You can also check out some online resources for more information comparison of different CFD software such as [Open-Source CFD Software Packages: Good Enough and Free](^2^) [Simulation of Thermofluids with Open Source Tools](^3^) [CFD Software Comparison Series] etc
Source:
(1) OpenFOAM | Free CFD Software | The OpenFOAM Foundation. https://openfoam.org/.
(2) HELYX-OS GUI for OpenFOAM | ENGYS. https://engys.com/products/helyx-os.
(3) CFD Simulation Software | SimFlow CFD: Free Download. https://sim-flow.com/download/cfd-simulation-software/.
(4) OpenFOAM | Free CFD Software | The OpenFOAM Foundation. https://openfoam.org/.
(5) HELYX-OS GUI for OpenFOAM | ENGYS. https://engys.com/products/helyx-os.
(6) OpenFOAM GUI - SimFlow CFD. https://sim-flow.com/openfoam-gui/.
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