[swanmodel-users] Diffraction

[<jul...@mu...>]

Hello,
I am trying to use diffraction in a model. It's a topography where large waves come close to shore, so that there is a large gradient when the sea finally becomes shallow.
I am nesting twice, and SWAN keeps giving me 0 wave height in all points in the finest mesh, unless I increase the number of smoothing steps to 50 or 70, depending on my resolution. I have been trying to change the resolution to no help. The coarser the grid the less smoothing steps I need, but I cannot decrease the resolution any more without compromising the accuracy. I have also tried varying the under-relaxation but that does not help.

SWAN gives me 0 wave height in all points after 4-5 calculation steps.
Does anyone have any advice as to how to get a stable solution with diffraction?

Thanks in advance

Best regards,
Juliane