open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello.
I'm running a 3D large case study after a 2D simulation (with good agreement to measurements) on the same domain.
In 3D runs, I imposed, at the offshore boundary, free-surface elevations and vertical profiles of u-v velocities (all conditions variable in time and space), resulting from a large scale model (I'm doing a sort of chaining with this model).
2D (i.e. depth average) results from 3D runs are quite good, very similar to the tel2d run, previously performed.
BUT if I look to vertical profiles of velocity, to start, the results are very different from measurements, but ALSO from the profiles I imposed as BC.
The resulted profiles are quite uniform with depth.
My question is: which are the parameters that strongly influence the vertical profiles of velocity?
I attached here the cas file, but I also tested different vertical turbulence model, without any improvements.
It seems like there's an imposed vertical profile....

Any advices will be very grateful, thanks.
Regards,

G

Hi,

In coastal hydraulics, vertical profile can be under the influence of mixing between salt and fresh water or thermal process. You have to check if in your measures, temperature and/or salinity are available.
With these parameters you can use dumping functions on the vertical.

Regards,

Ok, Thanks. It's my further step of study including thermal processes.
But, focusing on hydrodynamics, why vertical profile of velocities are uniform in depth although I imposed a not-uniform profile at the boundary?
I mean, also in the proximity of the boundary...
For sure, I'm missing some keywords...
Thanks

G

Hello,

Except buoyancy effects, the friction is the most important parameter. A Strickler of 50 is not a very high friction. The vertical diffusion coefficient is also important to transmit the effect of the friction on the bottom. In your steering file it seems to me that since you asked for a mixing-length model the vertical diffusion coefficient should be set to 1.D-6 instead of 0.05.

With best regards,

Jean-Michel Hervouet

Ok, do you mean that I should increase the bottom friction to have much more evident effects on the vertical profile of velocity?

Thanks.
G