Mesh problem

tuks

Hi everyone,

I am solving the flow in a cuboidal shape tank with rectangular c/s inlet & outlet. There is one problem

The area avg velocity@inlet & outlet are different from each other and also from actual velocity given as B.C at inlet.

(1)When i use the unstructured mesh i noticed that the avg velocity @inlet is less while @outlet is more than the specified B.C e.g. From POST, area avg V @inlet=0.002371 and @outlet=0.00261 while B.C is v=0.0025 by parabolic profile.

When i increase the surface resolution by refining mesh at both inlet & outelt, then velocity differences w.r.t B.C. is become more than earlier.

(2)For the structured mesh, when mesh at inlet & outlet surface is refined then velocity values come closer to but not equal to B.C. This happens upto certain level of refinement of mesh, beyond which solver ends with ERROR FINEMESS, fatal overflow.

Can anybody suggest what will be the ultimate solution? Is it necessary to refine mesh in rhe domain, rather making very fine at inlet & outlet.

IMP:: The profile@inlet, plotted by post is slightly different than given by CEL expression.

Thanks in advance

tuks