[dunapkt]

Hello everyone,

I have some questions about wall shear stress.

I am currently running a simulation using the Realizable k-epsilon model with both standard wall function and enhanced wall treatment. I am using meshes with the first cell y+ around 1 and around 30. The working fluid is liquid water (i.e., incompressible) and the Reynolds number is high enough to indicate turbulent flow.

When the wall is set to "No-slip condition," there is no problem with calculating wall shear stress. Both y+~1 and y+~30 meshes and both wall treatments give me the same value.

The problem occurs when the wall is set to "partial slip condition."

Wall shear stress is not much different between the standard wall function and the enhanced wall treatment. Also, when I compare these results with DNS data, the accuracy is sufficient (less than 10% error).

However, there is a significant difference between meshes with y+~1 and y+~30.

I believe there is a problem with calculating wall shear stress in the y+~30 case.

I have tried to figure out why this happens. I searched for information on wall shear stress calculation in the Fluent manual, but I couldn't find it. I would like to know how Fluent calculates wall shear stress.

Can anyone help me with this problem?

Thanks.

Best regards,