Changing turbulence model and getting error at outlet
Hi
I am simulating a turbine stator blade with different turbulence models. I have 1.3 million cells and the y+ is below 3. I get good results for ke, SSTand Komega and I don't have any convergence problem. But when I only switch the model to RSM and espesially RSM (BSL), I get this famous message after 10 iterations: "A wall has been placed at portion(s) of an OUTLET  boundary condition (at 10.0% of the faces, 1.4% of the area)  to prevent fluid from flowing into the domain.  The boundary condition name is: S1 Outlet.  The fluid name is: Air Ideal Gas.  If this situation persists, consider switching to an Opening type boundary condition instead" the percentage for area is smaller at first iterations but it reaches to 1.4% after 200 iterations. Can anyone says whats wrong with my problem? I don't change any boundary conditions, only the turbulence model is changed. Also MAX RMS doesn't reach even 10^4 for mass. how can I force the residuals to come down more than 10^5 is RSM models? 
Hi,
RSM turbulence models are more sophisticated than the other models and they usually need a better initial condition to converge. Have you tried using one of your previous solutions as the initial guess? Also consider making a mesh with slightly lower y+ or much larger y+. y+<1 is desired if you are not using wall functions, and if you are using one, then the desired y+ is (I think) more than 30. 
It is common for convergence problems with RSM models. They are very tricky to use. They require much higher mesh quality than 2eqn models. They also commonly resolve finer flow features than 2eqn models, so you will probably find vortices being created which convect to the outlet and cause some backflow at an outlet as they pass. This is just a warning so you can still proceed, but convergence will be harder.

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