[Nek5000-users] Non-dimensional wall distance y+ and Re:Total energy and wall gradients
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Tue Jul 20 04:38:34 CDT 2010
Howdy list,
last week, I finished writing the attached additions to userchk which
I'd like to share. The code computes shear stress, nearest grid point
distance and y+ on all wall faces - maybe this also helps JC with his
wall normal gradients.
Wall distance is saved in passive scalar 1 and y+ in passive scalar 2.
Those values are only stored on the wall faces, and are zero everywhere
else in the domain.
Shear stress is computed as follows:
1) Compute the gradient tensor (evaluated at the wall) and multiply with mue
S_ij=mue delta_j u_i
2) Project on wall normal direction (n_j is the vector normal to the
surface of interest, pointing away from it)
R_i=S_ij n_j
3) Vector sum
tau_wall=sqrt(R_i R_i)
For wall distance computation, I dug out a dusty routine from turb.f,
hoping it's not on the silent list of soon to be killed or altered nek
subfunctions.
Markus
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