Reynolds Stress Model

deeimproptus · November 2, 2011, 11:55

Working on flat plate with projections with jet impinging on it. Not pretty sure which model to use in Reynolds stress model -Linear Pressure-strain -Quadratic Pressure-strain -Low-Re Stress-Omega Tried with Low-Re Stress-Omega with second order upwind scheme but all the stresses along with KE and dissipation are oscillating. Played with it by reducing under-relaxation but oscillation are persistent. Do suggest...????

Far · November 3, 2011, 02:30

what is the maximum yplus in the domain. Quadratic Pressure-strain model is good, but it uses the epsilon as scaling variable, which might introduce error in solution, as it is well known that epsilon based models do not capture seperation and amount of seperation accuratly. On the other hand with omega based model, one can capture the boundary layer seperation more accuratly.

Aslo please refer to new model which uses the omega based model in near wall and Quadratic Pressure-strain model in the core flow. BSL-omega/SSG model by DLR

If you want to model the transition from laminar to turblence then use the three equation model by walter or metner gamma thetha model.

deeimproptus · November 3, 2011, 02:36

yplus is much less than 1
roughly around 0.33

I guess i have to give high initial guess values for dissipation

Far · November 3, 2011, 04:23

keep aspect ratio less than 100 (preferbly less than 50) and use double precision solver.

November 2, 2011, 11:55	Reynolds Stress Model	#1
deeimproptus New Member Deepchand Singh Negi Join Date: Oct 2011 Posts: 12 Rep Power: 15	Working on flat plate with projections with jet impinging on it. Not pretty sure which model to use in Reynolds stress model -Linear Pressure-strain -Quadratic Pressure-strain -Low-Re Stress-Omega Tried with Low-Re Stress-Omega with second order upwind scheme but all the stresses along with KE and dissipation are oscillating. Played with it by reducing under-relaxation but oscillation are persistent. Do suggest...????

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November 3, 2011, 02:30		#2
Far Senior Member Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,558 Blog Entries: 6 Rep Power: 54	what is the maximum yplus in the domain. Quadratic Pressure-strain model is good, but it uses the epsilon as scaling variable, which might introduce error in solution, as it is well known that epsilon based models do not capture seperation and amount of seperation accuratly. On the other hand with omega based model, one can capture the boundary layer seperation more accuratly. Aslo please refer to new model which uses the omega based model in near wall and Quadratic Pressure-strain model in the core flow. BSL-omega/SSG model by DLR If you want to model the transition from laminar to turblence then use the three equation model by walter or metner gamma thetha model.

November 3, 2011, 02:36		#3
deeimproptus New Member Deepchand Singh Negi Join Date: Oct 2011 Posts: 12 Rep Power: 15	yplus is much less than 1 roughly around 0.33 I guess i have to give high initial guess values for dissipation

November 3, 2011, 04:23		#4
Far Senior Member Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,558 Blog Entries: 6 Rep Power: 54	keep aspect ratio less than 100 (preferbly less than 50) and use double precision solver.