Vertical velocty at the wall (WALL boundary condition)

[logvinov]

Hello,
I have a question about the WALL boundary condition.

I consider 3D rectangular basin with uniform wind forcing on the top in E-W direction. I put periodic boundary conditions in E-W direction and WALL boundary conditions on the North and South.

So I put no slip condition GAMMA2 = -1.0d0 in the .in file. And the result was that the horizontal along the wall velocity (u) does go to 0 at the wall, but the vertical velocity (omega) does not go to 0 at the boundary. Could you explain what is going on there?

Also I have a question about the z-momentum equation. Is it just hydrostatic balance dp/dz=--rho*g, or is it something more complicated? I am asking because I am developing analytical solution as well and I figured that if we solve in terms of correction functions in boundary layers we will find that dp’/dz=d2w’/d2y (non dimensional, p’- correction function in BL). This requires that we have to consider the terms like VISC2 *(d2/d2x+ d2/d2y+ d2/d2z) w. Could you tell me whether ROMS pays attention to these terms?

Thanks a lot,
Evgeny

[kurapov]

Re:

I consider 3D rectangular basin with uniform wind forcing on the top in E-W direction. I put periodic boundary conditions in E-W direction and WALL boundary conditions on the North and South.

So I put no slip condition GAMMA2 = -1.0d0 in the .in file. And the result was that the horizontal along the wall velocity (u) does go to 0 at the wall, but the vertical velocity (omega) does not go to 0 at the boundary. Could you explain what is going on there?

It is called wind-driven upwelling, isn't it?

Re: BC. The model is hydrostatics so no boundary conditions on w. Plus, technically you are looking at w next to the boundary, not at the boundary (the grid is staggered).

At low resolution it may make more sense to use free-slip conditions.

[kate]

Yes, the w is computed from the continuity equation, so no option for anything fancier.