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Turbulent compressible and subsonic gas flow

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Old   May 30, 2005, 04:46
Default What do you mean by changing t
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What do you mean by changing the BC from wall to wall-functions? What set of BCs are you using for each? Wall-functions are always used on wall patches by the high-Re turbulence models.

If you want to add FoamX support for the transSonic option you will have to make a few changes to the configuration files which you will find in


Did you have to make any changes to the entries in fvSchemes to run with the transSonic option? If not then you do not need to make any changes in fvSchemes.
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Old   May 30, 2005, 11:44
Default Hi Weller About wall and wa
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Hi Weller

About wall and wall-function BC's, in the FoamX apears two options of BC for wall type: a) wall and b) wall functions. If I impose wall function in begining of the calculations, I have troubles. Otherwise, if I impose in the first moment the wall boundary as wall patch type, and after some convergence is achieved I swap it to wall-function, I have not problem. Reading your last advise, I have a question: what is the diference about wall and wall-function patch types (TrubFoam solver)? For rhoTurbFoam solver, two options apear for wall boundaries: adiabaticWall and wall-function. Are there the same or have its some diference? Why my calculations can't start with wall function boundary conditions?

About the BC's that I'm using are: at the wing surface, the wall boundaries discussed before. To the perpendicular planes at the wing tips, I impose the symmetryPlane. The farfield surface is a cylinder which is divided in two parts: the front part is defined as inlet BC and the other semi-cylinder is defined as outlet. About farfield, I have doubt if these conditions are the best. But I did'n find in FoamX other best option. In fact, the total pressure+velocity is better for inlet BC for transonic flows, but in such case what can I define as outlet BC?

After some tests I can left it available as tutorial case for OpenFoam Comunity, OK?

About modifications of FoamX, when will I find some free time, I will try change it and let it available for OpenFoam community.

I'm wonder with OpenFoam due how many option of convenction terms and others spatial and temporal operators discretisation are implemented. I can imagine the effort that your team spent to include it in this tool! In your experience, which of then is better for transonic flows?

Many Tanks once more!

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Old   May 30, 2005, 13:38
Default Have a look at the BCs written
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Have a look at the BCs written by FoamX when you choose the various options, alternatively have a look at the FoamX configuration files and you will see what is specified for each field for each option.

Basically the difference between wall and wall-functions is the former is for low-Re models with special near-wall modelling and the latter for high-Re models using wall-functions.

As for the best choice of discretisation scheme, it depends on your problem, mesh, choice of models and what you want from the simulation. Try a few to get a feel for their behaviour. Most of those implemented in OpenFOAM are standard and details are available in the literature.
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