[heysed]

Hello!

I have a trouble for my analysis.
I am performing VOF analysis to evaluate the drag reduction method, which is injecting the bubble into the water.
In more detail, I try to compare the shear stress near the wall with/without the injection of bubble in the turbulent boundary layers.

The issue is that the shear stress where the void fraction is high(i.e., the air) shows almost zero compare to that without the air injection.
I fully understand this is due to the large difference of viscosity between the water and air.
Furthermore, it is inevitable that the shear stress with the high void fraction is almost zero because the most air are near the wall due to the bubble buoyancy while the water is under the air.

However, it is not so acceptable that the bubble are not always near the wall because the distribution of the void fraction in a mesh instantly varies by the high turbulence.

Therefore, I need to correction method(e.g., library..) to prevent the overestimation of shear stress.
Could you guys give any comments or ideas?