open TELEMAC-MASCARET The mathematically superior suite of solvers

Dear Users,

I am running a tidal case on North Sea region and getting small amplitudes in comparison with measured data. It could be due to the wrong friction coefficient I use. The Low of Bottom Friction I chose as Chezy Law. I am battled with Friction Coefficient for the Bottom. The equation states: Cd=2g/(Ch)^2. My question is: Is Chezy coefficient Ch already specified somewhere in subroutine or I have to come up with it in order to be able to derive the Cd coefficient so I could enter it in steering file.
Also I know the Nikuradse Ks I can use as 0.05, so I could derive the Cd from there too, and then get Ch, but I am not sure in Cd=2[K/log(12h/Ks)]^2, what K stands for?
Could I get your advice if by experimenting with friction coefficient is enough to adjust the tidal amplitude difference or I still have to use Coefficient to Calibrate Tidal Range what I am trying to avoid so far?

Thank you in advance.

Kind Regards!

Violeta

Hi!
K is the Karman constant (K=0.4)- See the documentation-
Why don't you use a Nikuradese friction law (5)instead of 2. If you know the bed roughness you have to specify it in the steering file (FRICTION COEFFICIENT)

Good luck, Cath

Thank you very much Cath, will do so.

Kind Regards!

Violeta