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NOAA-EMC / WW3

WAVEWATCH III
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GSE alleviation for unstructured meshes #886

Open aliabdolali opened 1 year ago

aliabdolali commented 1 year ago

Is your feature request related to a problem? Please describe.

Garden Sprinkler Effect (GSE) is a known numerical issue in spectral wave models and is a result of de-integration of the wave field due to the finite bandwidth approach in spectral wave models. The structured part of WW3 has a method to smooth the GSE. Such a method does not work for the unstr part.

Describe the solution you'd like

A method to minimize GSE in global scale and on unstr meshes.

Describe alternatives you've considered

Introduce a diffusion operator within the advection scheme for unstr part of WW3.

aronroland commented 1 year ago

We can see the GSE even with a 1st order n-scheme, since it has the lowest possible cross diffusion. I suggest to implement a simple and fast diffusion operator and add that bit of diffusion, which is needed to alleviate it. A alternative would be an internally increased spectral resolution in the geographical advection part, however this will be costly...