open TELEMAC-MASCARET The mathematically superior suite of solvers

Hi,

1) As per the details provided in the reference manual, the option 'COMPATIBLE COMPUTATION OF FLUXES' is used to compute flux through the segment using weak formulation.

I would need the help for understanding the following things
a)Does the word 'segment' necessarily be solid-boundary segment?
b)What are all the scenarios we should use this 'COMPATIBLE COMPUTATION OF FLUXES' option?
c)What is the mathematical formula to calculate flux in weak formulation?

Additionally, i wish to understand more about 'C-U PRECONDITIONING' as it invokes the celerity in the places of depth. Why is the word PRECONDITIONING written in the option 'C-U PRECONDITIONING'?.

(PRECONDITIONING- ACCELERATING THE RATE OF CONVERGENCE OF THE SOLVER) Right?

Thanks in advance
Sathya

Hello,

1) on compatible computation of fluxes, it is very difficult to get the fluxes as they are computed in the program. For example an apparent flux across the solid boundaries in the output is not really taken into account in the mass balance. The option for compatible computation is a tentative way to get more accurate fluxes in this respect. A third and exact solution is uder way and will be hopefully in the next release.

2) The c-u preconditioning is used only when you use the primitive équations option (TREATMENT OF THE LINEAR SYSTEM : 1), which is now seldom used. In this case it is only a change of variables, the unknown depth being changed into the unknown celerity. In this case all the unknown (celerity and velocities) are in m/s so the system is unit independent, and it turns out to give a better conditioned system.

With best regards,

Jean-Michel Hervouet