[JulioPieri]

Hello guys!

I've being experimenting with different turbulence models to see how they affect the flow mixing.

I noticed that the "laminar" viscous/turbulence model, which doesn't apply any modeling, gives a much more realistic result [picture attached]. I know that RANS models average the quantities, and that's why they have a "diffused" look. Also, as expected, refining the mesh captures even finer structures on the laminar model - increasing the "resolution" of the figures.

For instance, the cavity tutorial (OpenFOAM) ran with laminar shows results that are visually much more appealing. Actually, the coarse mesh+laminar gives a (visually) similar result as the fine mesh+k-eps.

I suspect that the results look better, but all quantities may be much more inaccurate. Also, I suspect that a mesh-refinement study would lead to endless changes in the quantities.

I'd like to discuss:
1) Is it possible to extract any good info from a laminar model with a mesh that is, of course, not refined enough for a typical DNS simulation? I mean, besides the pretty figures... Do the figures represent anything actually?
2) Is there any situation where using laminar model would be useful, without an extremely refined mesh?
3) What are the cautions to take when using the laminar model?
4) On industrial applications, how to judge if the results from a "coarse" mesh using laminar/DNS are better/worse than the usual RAS model?

I'm having a hard time distrusting the figures... the solver also runs smoother than using turbulence models. Any ideas would be good!