open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello,

So it would be interesting to see what says version 7.1 but wait for the next revision V7P1R1 very soon. For problems not well posed, a new version may give very different results since you have an infinity of possible solutions. However it may be something else that we do not see.

With best regards,

Jean-Michel Hervouet

Dear Jean-Michel Hervouet,

Thank you so much for quick respond.

I am trying to figure out what cause this. I will post whenever I discovered.

Best Regards,

AMANJ

Hello,

It could be also that you have von Karman eddies behind the island, in which case such variations of velocities are normal, and the local turbulent diffusion is a sensitive factor, this is another hint. Normally we would expect that such eddies are triggered by the island, this can be observed in reality (this does not explain the difference between two versions if you do not use new features, however these oscillations may take time to settle and depend on bifurcations, so it can be sensitive to slight changes).

Regards,

JMH

Hello,

So, how to reduce this oscillations in velocities?
I have very long duration and with time steps of 5 and 2.5 and all the time this oscillations repeat continuously when ebb flow coming. It looks like cycle and keep repeating.

Thanks,

AMANJ

Hello,

I enclose a Word document where you can look at exercice 29 and its solution, giving formulas for the frequency of von Karman oscillations behind a bridge pier. If you can find the period of the oscillations you can know if they are natural and if they are natural why suppressing them? If you really want to cancel them you can increase the diffusion so that you get a Reynolds number where there are no oscillations.

With best regards,

Jean-Michel Hervouet

Hello dear Jean-Michel Hervouet,

Thank you so much for helping us in solving this issue. You are right, it was not related to the version of the TELEAMC. I changed the velocity diffusivity value and now I have the same result what we had in the previous version. Yes, I tested different values and I found that it has a great impact on reducing or absorbing oscillations. This document you shared is an amazing reference and I am sure everyone here can take benefit to reinforce their knowledge in TELEMAC suite.

Cheers,

AMANJ