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Hello to all


I've worked on a sediment transport model, I coupled Telemac2D with Sisyphe. I use Van Rijn as a formula to calculate sediment transport ( for the suspension and bed load). when I use only bed load transport I find logical resulats and when I use the formula for suspension sediment I find a surestimation ( value of sediment transport in the case of suspension sediment is more than in the case of bed load and that not logical )

is there a calibartion that should be used in the case a coupling telemac2D with sisyphe to calculate suspension sediment transport ?


thank you in advance
Jean

Dear Jean,
Thanks for your post. Please find below some tips to solve your problem:

(1) try another near-bed concentration formula, for example the Zyserman-Fredsoe (=1) to see how your model behaves

(2) control the value of the bed stress skin friction (\mu) that affects the total stress friction. Use the keywords:
SKIN FRICTION CORRECTION = 1 (default value)
RATIO BETWEEN SKIN FRICTION AND MEAN DIAMETER = 3. by default (this is the \alpha coefficient that used to compute the friction coefficient due to skin friction Cf', please refer to Sisyphe's users manual)

(3) control the value of the reference elevation. In particular, for the vR formula this is related to the value of the Nikuradse roughness ks, given in the hydrodynamics steering file

I hope it helps,

Best wishes

Pablo

Hello Pablo

thank you for your suggestions
I used :Zyserman-Fredsoe, but there is also surestimation.
I used the skin correction.
SKIN FRICTION CORRECTION = 1
RATIO BETWEEN SKIN FRICTION AND MEAN DIAMETER = 3
no change in the results
and for the reference elevation is Ks in tha case of VR formula

I didn't Understand where is the problem ??

Hi Jean,
try different values of the keyword RATIO BETWEEN SKIN FRICTION AND MEAN DIAMETER (the value =3 is the default value).

Best wishes,

Pablo

Thank you so much, i'll try to change the value of this ratio and see the results.

best regards
Jean