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Boundary conditions for RAS turbulence modeling

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Old   August 4, 2015, 09:25
Default Boundary conditions for RAS turbulence modeling
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Hello everybody,

I'm new to OF and not terribly experienced in CFD in general. I'm trying to simulate a gas flow in a Pipe intersection with two outlets and one inlet. The distribution between the outlets is known so I plan to use a pressure inlet and two velocity outlets.

The solvers that I have tested so far were SimpleFoam and PimpleFoam as I figured that due to turbulence a steady state solver might cause Problems. The velocity is way below sonic speed so I'm neglecting compressibility.

I have Problems with setting up the turbulence modeling which is neccessary as the Reynold's number is at about 12000. I have tried running it with some default values that I copied from tutorials (one of them suggests a mixing length of half the channel width and a turbulence intensity of 5%). If I turn turbulence modelling on the solution will however no longer converge.

Post processing with Paraview showed that a Vortex with incredible velocity formed at the pressure inlet, causing the solver to crash at some point.

I guess the problem lies somewhere in the configuration of the turbulence modeling as without it the solution converges easily. I'd be thankful if someone could help me with setting that up. This thread might belong into the solving forum but I was not quite sure so I'll post it here.

Thanks
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