I have in my Geometry some cavities with almost zero flow. I was wondering if openFoam comes with some embedded LES model that uses RANS in bulk flows and employs LES near the wall. If yes what is its name?
About the question in the title, my answer is yes, we're working on the subject and we're not aware of wall function for LES in OpenFoam for sucha task, while we had good results in separated flow with resolved LES with dynamic Lagragian model, and fair good results with Smagorinsky model and van Driest damping.
If you're thinking about DES, there are few choices in OpenFoam, but their working in the opposite way: RANS solution close to walls and LES formulation in bulk flow.
@Andrea I think I would be more interested in the LES near the walls and RANS in bulk flow. Because I have not yet found a RANS which is very good in flow separation zones, specially when applying the wall Functions. So the solution is just a fully resolved LES?
For my personal experience I can tell that separation is though for wall function, also with LES. There are improved LES wall function that are able to capture separation, that we implemented in our in-house code, but they're not available in OpenFoam. So yes, I think that a resolved LES is the only choice now, Ciao
Indeed you need a resolved LES to predict flow separation from a smooth surface (not a sharp edge).
Could you provide more details of your problem?
you can use resolved LES (3-4 nodes within y+
I have a turbulent flow in a pipe that at some point, its diameter gradually increases leading to flow separation. I also have some sudden cavities in the pipe.
so you produce also an adverse pressure gradient .... If your computational power is sufficient, I suggest using a wall-resolved LES and a dynamic SGS model. A mixed model is advisable
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