[mpas-developers] Vector Reconstruction

[Xylar S. Asay-Davis]

Hi Michael,

I don't think your attachment made it through.

I'll take a look at shallow water test case 2 to see what might be the
problem there. The value of uReconstructZ won't machine zero for a purely
zonal flow because the reconstruction in its current form will only
guarantee exact reconstruct of a constant flow in the tangent plane of the
cell, where as a zonal flow has components slightly out of the tangent
plane.  In my tests, I was seeing uReconstructZ smaller than uReconstructX
and uReconstructY by a factor of around 1e-6.

-Xylar


> Hi, Xylar.
>
> The module looks good to me -- very clean code. The only changes
> I'd suggest are to the comments at the beginning of the
> init_reconstruct() routine, and a few changes to indentation, as
> in the attached module_vector_reconstruction.F.
>
> This is most likely a problem in how I'm performing the
> computation given that both you and Todd have checked the
> reconstructed vectors, but I'm having trouble getting a zonal and
> meridional wind from the reconstructed vector in (x,y,z). Even
> plotting the magnitude of the reconstructed vector, sqrt(x^2 + y^2
> + z^2), I'm getting some unexpected values in the reconstructed
> wind speed field for shallow water test case 2 (with alpha=0).
> Given that we should have purely zonal flow for this test case,
> I'm suprised to see values in uReconstructZ of order 10. Do either
> you or Todd have any thoughts or suggestions?
>
> Cheers,
> Michael
>
>
> On Mon, Mar 22, 2010 at 03:30:39PM -0600, Xylar S. Asay-Davis wrote:
>> Attached is my proposed vector reconstruction code.  I have run several
>> sanity checks and it seems to work fine.  However, I haven't been able
>> to
>> get a full ocean core run with this code.  It is not clear to me if this
>> has to do with this code or with recent changes that Mark has made to
>> the
>> ocean core relating to 3D density.  I'll keep working with Mark to try
>> to
>> figure that out, but in the mean time it would be great to have Todd
>> and/or Michael test out this code to see if it will work for you.
>>
>> A registry entry for the coeffs_reconst is required as follows (already
>> in
>> the ocean core):
>> var real    coeffs_reconstruct ( R3 maxEdges nCells ) -
>> coeffs_reconstruct
>> - -
>>
>> Registry entries for  matrix_reconstruct, normal and  rbf_value are no
>> longer required by this code.
>>
>> -Xylar
>
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***********************
Xylar S. Asay-Davis
E-mail: xylar at lanl.gov
Phone: (505) 606-0025
Fax: (505) 665-2659
CNLS, MS B258
Los Alamos National Laboratory
Los Alamos, NM 87545
***********************