open TELEMAC-MASCARET The mathematically superior suite of solvers

Hi,
In the v8p2 manual, it indicates that when using the wave equation, the implicitation of the depth and velocity was imposed to 1 in release 6.0. In release 6.1, only implicitaton for depth was still imposed to 1.

I can't find any information from the old manual on why these two parameters were imposed to 1 when using the wave equation. The question I have is, should I set these two values to 1 when I use wave equation in v8p2 or should I leave them as default (0.55)?

Thanks.

Hello ewang,

Sorry, the lines you read in the TELEMAC-2D user manual should not be written now, they will be deleted in next release. They were usefull around release 6.2 just after some changes in releases 6.0 and 6.1, so that users could have found similar results between the 3 releases.

Anyway, from release 6.2, when using the two keywords TREATMENT OF THE LINEAR SYSTEM = 2 (wave equation), the 2 keywords IMPLICITATION FOR DEPTH and IMPLICITATION FOR VELOCITY can be chosen from 0.5 to 1.

More than 10 years ago, these 2 coefficients were set automatically to 1 for stability reason but it was then shown that it was not compulsory and now you can choose a value between 0.5 and 1. Choosing 0.55 can give you more accurate results (but maybe less stable).
Depending on what you want (more accurate or more stable), you are free to choose.

Hope this helps,

Chi-Tuan

Great. Thank you so much for the quick response.