[MITgcm-support] viscosity and corners

[Baylor Fox-Kemper]

Hi Mike,
   There is some discussion in

  A. Adcroft and D. Marshall, 1998: How Slippery are Piecewise- 
Constant Coastlines in Numerical Ocean Models? Tellus 50A, 95-108.

But really, the safe way to go is not to think in terms of the du/dy,  
but in terms of the viscous fluxes.  For slippery boundaries, the  
viscous fluxes normal to the boundary should vanish.  It is very easy  
to get confused otherwise!  In fact, the rotated coordinate system  
case in the Adcroft and Marshall can be made to be more sensible (and  
in agreement with the unrotated case) if boundary conditions are  
specified in terms of fluxes.

   -Baylor


On Apr 9, 2007, at 2:10 PM, Michael A. Spall wrote:

> This is not directly an MITgcm question, but I have a postdoc who
> is using a shallow water model on a c-grid and he is wondering how
> to treat biharmonic (or Laplacian) viscosity terms at corners.  The
> other boundary points are free-slip, and seem straighforward. For  
> example, at the u-point adjacent to corner, what do you assume
> for du/dy at the grid cell interface?  One u-point is in the  
> interior of the
> domain and the other needs to satisfy a no-normal flow condition at  
> the wall,
> yet if it does that it no longer is a free-slip boundary.  Does  
> anyone have
> a good reference for how this is done?  It must be written down  
> somewhere.
>
> Thanks,
> Mike
>
> -- 
> ==================================================
>
> Michael A. Spall
> Department of Physical Oceanography
> W.H.O.I. MS #21
> 360 Woods Hole Road
> Woods Hole, MA   02543
>
> mspall at whoi.edu
> (508) 289-3342 (office)
> (508) 457-2181 (fax)
>
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