I do not see the Physics mode selection in CFDTool

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I do not see the Physics mode selection in CFDTool

Submitted Questions
Hello,

         I have downloaded free version github_repo.zip and installed it in MATLAB on my MAC. I am learning how to use this tool with help from the Tutorials (in the documentation) and YouTube videos. It is working nicely so far. However, I am not ablle to see how I can access Navier-Stokes Equations as the equation/physics model. I do not see the Physics mode in my CFDTool. Is it possible that this free version is hard wired to Navier Stokes or some other form of basic fluid dynamic equations? Need your help to understand what is going on in this version of CFDTool.

   Thanks.

Subject Matter Expert,
Analytical Mechanics Associates
NASA Langley Research Center
Hampton, VA 23681
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Re: I do not see the Physics mode selection in CFDTool

Precise Simulation
Administrator
Is it possible that this free version is hard wired to Navier Stokes or some other form of basic fluid dynamic equations?
CFDTool is limited to a combination of flow and/or heat-transfer, while full physics mode selection and custom equations are available with the FEATool Multiphysics toolbox.

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Re: I do not see the Physics mode selection in CFDTool

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Using the link you provided, I could download the FEA Tool installer and install it as an Application in MATLAB under MyApps. I could use the option of N-S Equations in setting up a tutorial problem like flow over a 2D Cylinder and flow over a backward facing step. However, when I tried to do turbulent flow over a Backward Facing Step, I cannot select a Turbulence Model, which may be in OPENFOAM and not available in FEA Tool. The OPENFOAM button is grayed out. When we select N-S Equations but do not use a Turbulence Model, how does it work? Do we solve full N-S Equations using some discretizing scheme?

Do we have a free version of the OPENFOAM or do we have to purchase a license? We cannot save any model/solution created because it says this option is not available in Free Version. Is this correct?

On another note, when we use the option “Surface Plot”, and select pressure as the variable, it displays pressure everywhere in the flow field. The usage of the word surface pressure is a bit confusing because we tend to associate it as the pressure over a solid (model) surface.
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Re: I do not see the Physics mode selection in CFDTool

Precise Simulation
Administrator
Regarding turbulence models, at the moment only algebraic turbulence models are available with the built-in solver, but you can use RANS turbulence models with the external solvers OpenFOAM and SU2. OpenFOAM is free and open source, however needs to be installed separately depending on your system. If you are using a Windows PC you can download OpenFOAM from here:

https://sourceforge.net/projects/openfoam/files/v2012/OpenCFD-OpenFOAM-v2012-DP-mingw-crosscompiled-WindowsInstaller.exe/download

and for Linux or Mac https://www.openfoam.com/download/current-release

once installed and recognized the "OpenFOAM" button should be active (not greyed out) and solver available to use.

> Do we solve full N-S Equations using some discretizing scheme?

Yes, the full NSE are solved using the finite element method with the built-in solver, and FVM with OpenFOAM or SU2.

> On another note, when we use the option “Surface Plot”, and select pressure as the variable, it displays pressure everywhere in the flow field. The usage of the word surface pressure is a bit confusing because we tend to associate it as the pressure over a solid (model) surface.

Yes, I can see the confusion. I think for 3D models it might correspond better (as it refers to plotting an expression on a surface), but I think in your case you mean that surface pressure would be analogous to a line plot in 2D? You can also do line plots with the "Point/Line Evaluation..." option in the "Post" menu.