resolving BL in openlb
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Dear OpenLb developer,
First of all I should thank you for sharing this great opensource code. I have some questions regarding the LES SGS model that you developed in the source code. In the aorta_example, there is a function that compute y_plus at the boundaries, it seems that the value is less than one all the time, considering that the (a) wall boundary in LBM is like staircase and (b) LES wall BL resolving is very tricky (even in FVM which uses unstructured mesh) how is it possible to reach that value? I was wondering if it is possible to resolve boundary layer in LBM. I will be appreciated if you would please let me know whether there is any recent development in capturing BL in LBM, I am specifically interested in turbulet wallshearstress and the way you resolve BL in the boundaries.
Many thanks again
RyanDear Ryan,
thank you for your feedback. The written value is not correct and the functor will hopefully replaced in the next release. We are not able to resolve the flowfield entirely. You can have a look at the laminar/poiseuille3d example, there you find a working calculation of the wall shear stress. The criteria to decide if a boundary layer is resolved, are the same for LBM and FVM. Unfortunately, OpenLB does not feature grid refinement at the moment. So it is hardly feasible to address wall-resolved LES at high Reynolds numbers.
Best,
Marc
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