wall shear stress formulation
Dear All!
what is the correct equation for finding wall shear stress in X and Y direction in ANSYS FLUENT FOR WRITING UDF? I assume that for X direction wall shear stress=mu*du/dy and for Y DIRECTION =mu*dv/dx .please confirm. |
Quote:
Unfortunately, there is a big bug in computing wall shear stress in FLUENT. To write a UDF for this purpose, use normal vectors of each element to project tensor elements. PS: T=2.0*mu*D ; D=0.5*(del(v)+trans(del(v))) |
UDF help
Dear Mr. Amir,
Thanks for your suggestion.I tried this concept for writing udf for wall shear but I could not implement del(v) and trans( v) functions. Actually in the previous UDF , which you had corrected for wall shear, results are coming but I am not getting boundary layer velocity gradients.I am getting velocity gradients just in the flow direction . Now ,I have written new UDF with suggestions from people on net,where dudy MACRO is replaced by f-u(f,t)-c-u(c,t) etc. concept.I have posted this UDF on this site. I am getting some problem with it. please help to rectify the problem. My aim is to model wall shear in a way that ,instead of no slip condition,non-zero velocity is obtained in the transverse direction(prep. to flow). Thanks for all your help. Rakesh |
Dear Amir
Quote:
agha man ye moshkele kheili bozorg ba hamin ghaziyeye wall normal and shear stress daram mitunid komakam konid plz? |
Can anyone help me with writing the udf that amir said???? i really need it! i have the same problem in calculating WSS with FLUENT!
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