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Hi, I was running a rectangular channel flow simulation in Telemac3D and comparing the results output between 2D slf and 3D slf. I noticed that there are differences between depth-averaged values calculated from the 3D slf and direct values obtained from the 2D slf.

I am a bit confused why that happened and think that experts here might have a quick answer...

If I would like to compare depth-averaged values from a Telemac3D simulation against values output from a standalone Telemac2D simulation, should I use the values from the 2D slf output (from Telemac3D) or the manually calculated depth-averaged values from the 3D slf.

Thanks in advance!

Hello,

Just to be sure what you mean: results output between 2D slf = 2D RESULT FILE and 3D slf = 3D RESULT FILE?

I am interested in how you calculate depth-averaged values from the 3D RESULT FILE, can you explain?

If I were you, I would compare 2D RESULT FILE from a TELEMAC-3D computation with RESULTS FILE from a TELEMAC-2D computation.

You can find how TELEMAC-3D computes depth-averaged values in VERMOY subroutine.

Hope this helps,

Chi-Tuan

Yes, for 2D and 3D slf I mean the RESULT FILE.

To calculate depth-averaged values from the 3D RESULT FILE, I simply averaged the values taken from each layer. I suspect this is the cause of the differences that I spotted because the method in the VERMOY subroutine seems to be very different. How are the depth-averaged values computed in the VERMOY subroutine specifically?

Thanks again Chi-Tuan.

Hello,

As you may know, a depth-averaged value of F e.g. is defined as 1/h int from bottom to top of F.
As written in a comment of the VERMOY subroutine, the integral is computed following the trapezoid rule which is a classical method to approximate an integral.

The result may be different from your simple arithmetic average.

Hope this helps,

Chi-Tuan