How to define porosity in Ansys CFX ?

 ANSYS CFX is another software for computational fluid dynamics (CFD) that can also simulate various phenomena involving fluid flow, heat transfer, and chemical reactions. Similar to ANSYS Fluent, ANSYS CFX can also model porous media, such as packed beds, filter papers, perforated plates, etc

To define porosity in ANSYS CFX, you need to specify a domain in which the porous media model is applied and the pressure loss in the flow is determined by your inputs. There are two approaches to set up the porous media model. 

In addition to the source term in the momentum equation, you also need to define the porosity value for the porous domain. The porosity is a dimensionless quantity that indicates the fraction of the domain volume that is occupied by fluid. The porosity affects the calculation of material properties, heat transfer, reaction source terms, and body forces in the porous medium. You can enter a constant value for the porosity or use a user-defined function (UDF) to specify a spatially varying porosity

To define porosity and resistance coefficients in ANSYS CFX using the graphical user interface (GUI), you can follow these steps:

• Go to Domain panel and select the domain that you want to model as porous.
• Enable Porous Media option and click Edit.
• In the Porous Media panel, enter the value for porosity or select UDF option if you have a UDF for porosity.
• Select either Standard or Power-Law option for Resistance Formulation.
• Enter the values for resistance coefficients or select UDF option if you have a UDF for resistance coefficients.
• Click OK to close the Porous Media panel and Apply to close the Domain panel.

To define porosity and resistance coefficients in ANSYS CFX using text commands (TCL), you can follow these steps:

• Enable TCL mode by using the command: tcl
• In TCL mode, type set domain-name [get "Domain:domain-name"] where domain-name is your domain name.
• Type set domain-name.Porous Media = On to enable Porous Media option.
• Type set domain-name.Porosity = value or set domain-name.Porosity = "UDF:udf-name" where value is your porosity value or udf-name is your UDF name for porosity.
• Type set domain-name.Resistance Formulation = "Standard" or set domain-name.Resistance Formulation = "Power-Law" to select Resistance Formulation option.
• Type set domain-name.Resistance Coefficients = "value1 value2" or set domain-name.Resistance Coefficients = "UDF:udf-name" where value1 and value2 are your resistance coefficients or udf-name is your UDF name for resistance coefficients.
• Type end to exit from TCL mode.

For more information and examples on how to define porosity in ANSYS CFX, you can refer to these sources:

• ANSYS CFX-Solver Modeling Guide - 4.6 Porous Media 
• Entering parameters at CFX’s porous domain - Ansys Learning Forum 
• Porous medium Settings(porosity settings) in CFX - CFD Online 

You can also watch this video that demonstrates how to simulate flow through porous media using ANSYS CFX:

•  #Ansys CFX Tutorial | Flow Through Porous Media 

How to define porosity in Ansys Fluent ?

 ANSYS Fluent is a software for computational fluid dynamics (CFD) that can simulate various phenomena involving fluid flow, heat transfer, and chemical reactions. One of the features of ANSYS Fluent is the ability to model porous media, such as packed beds, filter papers, perforated plates, etc

To define porosity in ANSYS Fluent, you need to specify a cell zone in which the porous media model is applied and the pressure loss in the flow is determined by your inputs. There are two approaches to set up the porous media model:

In addition to the source term in the momentum equation, you also need to define the porosity value for the porous cell zone. The porosity is a dimensionless quantity that indicates the fraction of the cell volume that is occupied by fluid. The porosity affects the calculation of material properties, heat transfer, reaction source terms, and body forces in the porous medium. You can enter a constant value for the porosity or use a user-defined function (UDF) to specify a spatially varying porosity

To define porosity and resistance coefficients in ANSYS Fluent using the graphical user interface (GUI), you can follow these steps:

• Go to Cell Zone Conditions panel and select the cell zone that you want to model as porous.
• Enable Porous Zone option and click Edit.
• In the Porous Zone panel, enter the value for porosity or select UDF option if you have a UDF for porosity.
• Select either Standard or Power-Law option for Resistance Formulation.
• Enter the values for resistance coefficients or select UDF option if you have a UDF for resistance coefficients.
• Click OK to close the Porous Zone panel and Apply to close the Cell Zone Conditions panel.

To define porosity and resistance coefficients in ANSYS Fluent using the text user interface (TUI), you can follow these steps:

• Enable the use of parameters in TUI by using the command: /define/parameters/enable-in-TUI? yes
• In the TUI, type /define/boundary-conditions/set/fluid
• Select the appropriate cell zone by typing its name and hitting Enter.
• Type y to enable Porous Zone option.
• Enter the value for porosity or type udf if you have a UDF for porosity.
• Type standard or power-law for Resistance Formulation.
• Enter the values for resistance coefficients or type udf if you have a UDF for resistance coefficients.
• Type end to exit from fluid boundary conditions.

For more information and examples on how to define porosity in ANSYS Fluent, you can refer to these sources:

• ANSYS FLUENT 12.0 User’s Guide - 7.2.3 Porous Media Conditions 
• Porous medium simulation. Fluid porosity. - Ansys Learning Forum 
• How to define a parameter for Porosity through ANSYS Fluent TUI … 
• Question about Solidification/melting model in Fluent ⁵

You can also watch these videos that demonstrate how to simulate flow through porous media using ANSYS Fluent:

• #Ansys Fluent | Flow Through Porous Media | Part 1/2 
• Ansys Fluent 2020 R1 - Porous Medium Tutorial 
• ANSYS Fluent Tutorial | Application of Periodic Boundary Conditions in Fluid Flow & Heat Transfer | 

#12steps Video Tutorial Ansys Transient Thermal - How to define different temperatures on various elements on one geometry ?

First of all, U need to know what are APDL commands and what to use for. 

 The IC command in Ansys APDL is used to specify initial conditions at nodes for a static or transient analysis . It allows you to define the initial values of the degrees of freedom, such as displacements, rotations, temperatures, magnetic potentials, etc. The syntax of the IC command is:

IC, NODE, Lab, VALUE, VALUE2, NEND, NINC

where:

• NODE is the node at which the initial condition is applied. You can use ALL to apply to all selected nodes, P to enable graphical picking, or a component name.
• Lab is the degree-of-freedom label for which the initial condition is specified. You can use ALL to apply to all appropriate labels.
• VALUE is the initial value of the degree of freedom. It defaults to the program default for that degree of freedom (0.0 for structural analysis, TUNIF for thermal analysis, etc.).
• VALUE2 is the second-order degree of freedom value, mainly used for non-structural DOF where VELX can’t be used. It defaults to the program default for that degree of freedom (0.0 for structural analysis).
• NEND and NINC are optional arguments that specify the same initial condition values at a range of nodes from NODE to NEND (defaults to NODE), in steps of NINC (defaults to 1).

Some notes and examples of using the IC command are:

• The IC command is valid only for a static analysis and full method transient analysis (TIMINT,ON and TRNOPT,FULL). For the transient, the initial value is specified at the beginning of the first load step, that is, at time = 0.0 .
• Initial conditions should always be step applied (KBC,1) and not ramped .
• If constraints (D, DSYM, etc.) and initial conditions are applied at the same node, the constraint specification overrides .
• For thermal analyses, any TUNIF specification should be applied before the IC command; otherwise, the TUNIF specification is ignored .
• The degree-of-freedom values start from zero, or the first value given in the table when table name is specified .
• To match the nonzero initial condition value with the initial value for degree-of-freedom constraint, use a table for the degree-of-freedom constraint .
• The values are in the nodal coordinate system and in radians for rotational degrees of freedom .

For example, to apply an initial temperature of 100°C to all selected nodes, you can use:

IC, ALL, TEMP, 100

To apply an initial displacement of 0.01 m in the x-direction and an initial velocity of 5 m/s in the y-direction to node 5 and node 10, you can use:

IC, 5, UX, 0.01
IC, 5, VELY, 5
IC, 10,, , , 10

You can find more information about the IC command and other Ansys APDL commands in the Mechanical APDL Command Reference . You can also visit the Ansys Learning Forum  to ask questions and learn from other users. I hope this helps you understand the IC command better. 😊

What is better? SpaceClaim or Design Modeler in Ansys ?

 SpaceClaim is a 3D CAD modeling software that runs on Microsoft Windows and is developed by SpaceClaim Corporation, which was acquired by Ansys in 2014². SpaceClaim allows you to quickly create, edit, or modify imported geometry without the complexity associated with traditional CAD systems. You can use SpaceClaim for various purposes, such as design and concept modeling, reverse engineering, 3D printing, model preparation for simulation and manufacturing, and more⁴.

SpaceClaim uses direct modeling techniques that let you manipulate the geometry with simple gestures, such as pull, move, fill, and combine. You can also add constraints and parameters to your sketches and save them with a block recording function. SpaceClaim can import and export various file formats, such as STEP, IGES, STL, etc⁵. SpaceClaim is integrated with Ansys Simulation packages as a built-in 3D modeler².

Source: 

(1) Ansys SpaceClaim: Tips and Tricks | Ansys Virtual Academy. https://www.youtube.com/watch?v=ZI02A1cS8ME.

(2) Ansys SpaceClaim | 3D CAD Modeling Software. https://www.ansys.com/products/3d-design/ansys-spaceclaim.

(3) SpaceClaim - Wikipedia. https://en.wikipedia.org/wiki/SpaceClaim.

(4) What's New in Ansys SpaceClaim 2020 R2. https://www.youtube.com/watch?v=faAKd_aOq6w.

(5) ANSYS Discovery SpaceClaim - ANSYS 19 Overview. https://www.youtube.com/watch?v=Dz-k2f1Taq4.

(6) ANSYS SpaceClaim: Everything to Know | Explore the Future of .... https://sunglass.io/ansys-spaceclaim/.

(7) Ansys SpaceClaim Reviews 2023: Details, Pricing, & Features - G2. https://www.g2.com/products/ansys-spaceclaim/reviews.

(8) https://ketiv.com/academy/ansys-virtual-academy/.

What is better: Ansys SpaceClaim or Ansys Design Modeler?

There is no definitive answer to which tool is better, as it may depend on your preferences, needs, and use cases. However, I can provide you with some information and comparisons based on the web search results that I have found.

- ANSYS DesignModeler (DM) and ANSYS Discovery SpaceClaim (SC) are both 3D modeling tools that can be used for creating and modifying geometry for simulation purposes¹.

- DM and SC use different geometry modeling kernels: DM uses Parasolid, while SC uses ACIS². This means that moving data between DM and other tools that use Parasolid (such as SOLIDWORKS) is easier than moving data between SC and those tools, as there is no need for translation². However, SC can also import and export various file formats, such as STEP, IGES, STL, etc³.

- DM has a history tree that records the sequence of operations performed on the geometry, while SC does not have a history tree by default (although it can be enabled with an optional feature)². This means that DM allows you to easily modify the parameters and constraints of the geometry at any stage, while SC requires you to use the block recording function to save and replay the operations⁴.

- SC has a more intuitive and user-friendly interface than DM, as it uses direct modeling techniques that allow you to manipulate the geometry with simple gestures such as drag, pull, move, etc³. SC also has more advanced features such as repair, simplify, optimize, etc., that can help you prepare the geometry for simulation faster and easier³.

- Both DM and SC have their own advantages and disadvantages, and you may need to use both of them depending on the situation. For example, you may want to use DM for parametric design and optimization, and use SC for complex geometry creation and modification².

Source:

(1) Design Modeler Vs SpaceClaim - Ansys Learning Forum. https://forum.ansys.com/forums/topic/design-modelller-vs-spaceclaim/.

(2) When DesignModeler is a better choice than SpaceClaim. https://forum.ansys.com/forums/topic/when-designmodeler-is-a-better-choice-than-spaceclaim/.

(3) Compare ANSYS DesignModeler vs ANSYS Discovery SpaceClaim. https://comparisons.financesonline.com/ansys-designmodeler-vs-ansys-discovery-spaceclaim.

(4) Compare Ansys Discovery vs Ansys SpaceClaim 2023 | Capterra. https://www.capterra.com/simulation-software/compare/245795-124168/Ansys-Discovery-vs-Ansys-SpaceClaim.

#12steps Video Tutorial - Conjugate Heat Transfer on Ansys Fluent

 This is the first episode of 12 steps video's tutorials. I hope You like it :) 

First U need to know what is Conjugate Heat Transfer. 

Conjugate heat transfer is a type of heat transfer analysis that involves both solids and fluids. It takes into account the effects of conduction in solids and convection in fluids, as well as the interactions between them at the interface. Conjugate heat transfer is important for many engineering applications, such as cooling of electronic devices, heat exchangers, combustion chambers, and solar collectors. ¹²

Some examples of conjugate heat transfer problems are:

- A heat sink that dissipates heat from a power supply unit by increasing the surface area in contact with the air flow generated by a fan. ²

- A shell-and-tube heat exchanger that transfers heat between two fluids separated by a thin metal wall. ²

- A nuclear reactor core that transfers heat from the fuel rods to the coolant fluid. ⁴

To solve conjugate heat transfer problems, one needs to use a numerical method that can handle both solid and fluid domains, as well as the coupling conditions at the interface. Some of the methods are:

- The domain decomposition method, which divides the problem into subdomains and solves them separately, then matches the solutions at the interface. ¹

- The finite element method, which discretizes the problem into elements and applies variational principles to obtain a system of equations. ²

- The finite volume method, which discretizes the problem into control volumes and applies conservation laws to obtain a system of equations. ³⁴

Below two parts of video tutorial of Conjugate Heat Transfer in Ansys Fluent (#12steps series)

Source: 

(1) Conjugate convective heat transfer - Wikipedia. https://en.wikipedia.org/wiki/Conjugate_Convective_Heat_Transfer.

(2) Conjugate Heat Transfer | COMSOL Blog. https://www.comsol.com/blogs/conjugate-heat-transfer/.

(3) Solving Conjugate Heat Transfer problems - Computational Fluid Dynamics. https://www.computationalfluiddynamics.com.au/conjugate-heat-transfer/.

(4) Conjugate Heat Transfer Simulation: Best Practices | SimScale. https://www.simscale.com/blog/cht-best-practices/.

Quick Tip: How to avoid Incorrect Wave Height in Ansys Fluent

According to my video and web search, this is a common issue that many Fluent users face when simulating open channel flow with wave boundary conditions . Some possible causes and solutions are:

• The wave height may be affected by the mesh quality and resolution. You may need to refine your mesh near the free surface and use a finer time step to capture the wave dynamics more accurately .
• The wave height may also depend on the wave theory and spectrum that you choose for your boundary conditions. You may need to adjust the parameters such as wave length, wave period, wave amplitude, wave direction, etc. to match your desired wave characteristics .
• The wave height may be influenced by the numerical schemes and relaxation factors that you use for your solution methods. You may need to use a higher order scheme such as QUICK or MUSCL and lower the relaxation factors for pressure and volume fraction to improve the stability and accuracy of your solution .

You can find more details and examples on how to perform these steps in the following resources:

• A video tutorial on how to model a tank discharge flow using VOF model in Ansys Fluent .
• A video tutorial on how to model an open channel flow with wave using VOF model in Ansys Fluent ³.
• A forum thread on how to avoid incorrect wave height in Ansys Fluent.
• A forum thread on how to use wave period for input in Fluent.
• The Ansys Fluent User’s Guide, especially Chapter 23: Using the VOF Model.
• The Ansys Fluent Theory Guide, especially Chapter 18: Volume of Fluid Model Theory.

I hope this helps you avoid incorrect wave height in Ansys Fluent and achieve your desired simulation results. If you have any other questions, please feel free to ask me. 😊

Quick Tip: How to fix Error: GENERAL-CAR-CDR in Ansys (Fluent)

 The error message Error: GENERAL-CAR-CDR: invalid argument [1]: improper list means that there is a problem with the scheme code or the UDF (user-defined function) in your case or data file . Some possible solutions are:

• Save the case and data file and try to reopen it.
• Reset the Fluent Setup tab and try opening the mesh.
• Remesh the geometry and reopen in Fluent.
• Change the material definition from “Solid” to “Fluid” in Design Modeler.
• Change the transient to steady if you are using evaporation-condensation as the phase interaction mechanism.
• Check the syntax of your UDF and make sure it follows the new rules in Fluent 6.2.16 or later.

I hope this helps you resolve the error. If you need more assistance, please visit the Ansys Learning Forum or contact Ansys Support . Have a nice day! 😊

Sources:

1. smartadm.ru

2. cfd-online.com

3. forum.ansys.com

4. forum.ansys.com

In Polish 

Błąd: GENERAL-CAR-CDR oznacza, że wystąpił problem z kodem Scheme w programie Ansys Fluent. Scheme to język programowania używany do pisania funkcji zdefiniowanych przez użytkownika (UDF) lub makr w Fluent ¹. Błąd ten pojawia się, gdy Fluent oczekuje listy wartości, ale otrzymuje inną wartość, np. fałszywą (#f) ².

Możliwe przyczyny tego błędu to:

• Niepoprawna składnia lub brakujące znaki w kodzie Scheme
• Niezgodność typów danych lub argumentów w funkcjach Scheme
• Nieprawidłowe ustawienia lub opcje w Fluent

Możliwe rozwiązania tego błędu to:

• Sprawdzenie i poprawienie kodu Scheme, upewniając się, że wszystkie nawiasy i cudzysłowy są zamknięte i dopasowane
• Sprawdzenie i poprawienie typów danych i argumentów w funkcjach Scheme, upewniając się, że są zgodne z dokumentacją Fluent
• Zapisanie i ponowne otwarcie pliku przypadku i danych
• Zresetowanie zakładki ustawień Fluent i ponowne otwarcie siatki
• Przemieszanie geometrii i ponowne otwarcie w Fluent

Możesz znaleźć więcej informacji i przykładów na temat tego błędu na stronach internetowych ³⁴. Mam nadzieję, że to ci pomoże. 😊