Cannot apply "current variation from HD simulation" in SW module of MIKE21/3

Hi all,

I am running a MIKE21/3 Coupled Model with Hydrodynamic (HD), Sand Transport (ST) and Spectral Wave (SW) Modules. Whenever I try applying "current variation from HD simulation" in the SW module, the SW iterations never converge and I get really small (unrealistic) wave value output. I've tried almost everything... applied a Manning Map with increased resistance at the boundaries, using a constant water level, created a more appropriate sediment transport table...

My simulation runs fine if I apply no currents to the wave simulation in the SW module. Any ideas as to what might be going on would be much appreciated.

Cheers, Tom

Hello Thomas,

Have you checked your Solution Technique parameters in the SW module? If it is a convergence problem in the SW module my first attempt to solve this would be to check the time step values there.

Kind regards,
Ricardo Machado

Hi Ricardo,

Thanks for that, but I already have the iterations set at 500 and a tolerance of 0.001 and relaxation factor of 0.1 (which I think is ample). I'm just wondering whether it has anything to do with the fact that the SW module wants currents from the HD module, and the HD module wants radiation stress from the SW module... But the dynamic feedback between modules is the whole point of the Coupled Model!

If anyone else has had similar issues I'd be interested to hear.

Cheers, Tom

Could the problem originate from your HD module then?
Whenever building a complex coupled model the best approach is to start by building and stabilizing the modules one by one. First the HD module, then SW and then ST.
Following this procedure, you can look at the results of each module before they interact with each other and see if their results are stable and make sense. That will make it easier to understand where the problem is and how to solve it.
I hope this helps as unfortunately I have no other clues as to what might cause your particular issue.