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Hi,

I can't seem to get rid of my recirculation problem. I have a model with one upstream boundary and two intakes at which ends I have my downstream boundaries. When I compute my model with a 0.026 Manning, it works well. However, now, for research purposes, I need to model it with 0.030 and I have recirculation happening at the downstream boundary. Any tip as to how to get rif of this?

Hello

The recicrculation is not only the matter of bed friction, it depends on a large number of parameters(bathymetry, secondary currents, turbulences, viscosity, velocity field, ...)

If you have some recirculations in the vicinity of your boundary, you need to check up the cause(s) between the uplisted parameters. If the recirculation has a physical interpretation, you have to make do and maybe lengthen your model in order to keep away your downstream boundary.

Some other hints that can help to get rid with this recirculation is to decrease velocity diffusivity, to refine locally the mesh and re-interpolate bathymetry. You can also revisit your calibration procedure by introducing several sub-zones for the Manning coefficient (you can do it directly with Blue Kenue or use the user subroutine strche.f)

I hope that this helps

with my best regards

Riadh ATA