Hi everyone.

I want to know the shear stress between the liquid (water) surface and air. Is this shear stress different from that between solid wall and air?

Thanks, akr

It is usually differ becuase at gas-liquid interface the relative velocity (vg-vw) was not the same as the gas velocity at the wall hence the shear stress not the same.

K. Baker

Hi, Baker. Thank you for your reply.

Now I want to model gas flow in the chamber. This is my experimental apparatus. Acutually, in the apparatus, there is the liquid layer, approximately 30 mm in depth. So when I model the gas flow in this apparatus, I create a grid without the liquid layer. In the model, I set the boundary condition of the bottom face (this is acutually liquid surface) wall boundary and no-slip condition. So now I want to set a specified shear between interfaces of gas and liquid. Do you know what to do for? Is it O.K. to set the no-slip condition?

Thanks, akr

I think if you want to set interfacial shear you need to consider the wall as a moving wall and set its velocity equal to the highest velocity of liquid (Ui) I am not try this method in my calculation yet but I have a paper consider the interface as this so try it and see if it useful for you?

REGARDS Khalid Baker