[MITgcm-support] nonhydrostatic w boundary condition

[Martin Losch]

In nonhydrostatic mode, vertical velocities are still computed from "div U = 0". If the 3D pressure solver has converged perfectly, this wVel is the same as the one obtained from stepping the w-equation. If not (in practice you have only finite accuracy), the differences are small, and you have to make a decision which equation you want to satisfy, dw/dt = Gw, or delU=0. In the MITgcm, delU=0, as far as I know. However, W at the open boundary is reset to the prescribed value (see integr_continuity).

If (div U) is not zero, you'll generally get extra sources in the tracer equations. I bet that this will also happen along the open boundaries.

Martin

On Apr 16, 2010, at 7:42 PM, David Hebert wrote:

> In nonhydrostatic mode it looks like it is possible to prescribe all components (u,v,w) of velocity at the boundaries. Is that right? Are there consequences if continuity ("del dot U") is not strictly matched?
> 
> Thanks,
> 
> David
> 
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