||November 26, 2012 00:45
Originally Posted by TQIM
My geometry has two inlets and one outlet. I want two different flow regimes at each inlet. From one inlet I want turbulent flow and from other Laminar flow. Is it possible in Star ccm+. If yes, then please tell me how to do it.
Physically these flows exist but they are difficult to model. Star-CCM does not support both models in the same domain, either only turbulent or only laminar, with exception of transitional turbulence models being used. You can try the transitional models mentioned. It is hit or miss (likely a miss) but it might do better than a non-transitional model.
The problem is not in the inlet and outlet boundary conditions. The issue is which governing equations to use in the domain (i.e. which laminar/turbulence model to use).
The best way to proceed is to choose your favorite turbulence model and apply 0% turbulence at your laminar inlet (that's an ad-hoc definition for laminar flow, flow with no turbulence). So use 0% turbulence intensity at that inlet (length scale is arbitrary if intensity is set to 0). Use the correct turbulence intensity % for the turbulent inlet. You can do this for transitional or non-transitional model.
Just don't do the other way around and use a laminar flow model since that would result in only laminar flow (no turbulence).