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LANL Contributions to PArallelized Large-eddy simulation Model (PALM)
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Spatial filter for log law of the wall #57

Open cbegeman opened 4 years ago

cbegeman commented 4 years ago

Since log law of the wall holds in a spatially-averaged sense, Bou-Zeid et al. (2015) filter the resolved velocity near the wall by 2 times the grid size. The current version of the code has some averaging but perhaps not enough: https://github.com/xylar/palm_les_lanl/blob/c293074463bb0bda5a6796182b56793a1d163d91/trunk/SOURCE/surface_layer_fluxes_mod.f90#L1054-L1055 (these terms are used to define the surface stress). What do you think about averaging u(i,j,k),u(i+1,j,k),u(i,j+1,k),u(i+1,j+1,k) for the surface stress calculation instead (and likewise for v)? It's probably a minor effect but I don't think it would hurt to implement.

xylar commented 4 years ago

I agree, more spatial averaging would likely make some sense. I think the averaging that you point to is just to move from the respective edges to cell centers, so it's not really intended for smoothing purposes.