open TELEMAC-MASCARET The mathematically superior suite of solvers

Dear All,

I am trying to simulate tracer transport as conservative, but found the mass is not balance with time depends to the diffusion.

How to produce a well mass balance of conservative tracer transport, as I used OPTION FOR THE DIFFUSION OF TRACERS = 2 but divergence occurred with variable of COEFFICIENT FOR DIFFUSION OF TRACERS? The model runs with finite element scheme.

FIQU = FINAL QUANTITY
Cumm. QCST = QUANTITY CREATED BY SOURCE TERM (cumulative)
TOQL = TOTAL QUANTITY LOST
cfdot = COEFFICIENT FOR DIFFUSION OF TRACERS

Many thanks,
Amyrhul

Hello,

You should have a mass conservation at least of the order of the relative accuracy of the solvers, unless you use the method of characteristics for the advection of tracers. An important parameter is whether you favour fluxes or values on prescribed boundaries. Unfortunately I am travelling and do not remember the corresponding keyword but it is something like OPTION FOR THE FLUXES AT BOUNDARIES, 1 is for getting the prescribed values, 2 is for getting the correct fluxes (hence the correct mass conservation), and there is one figure per liquid boundary, separated by semi-colons.

With best regards,

Jean-Michel Hervouet

Hello J-M Hervout,

I used TYPE OF ADVECTION = 14;5;14;1, means the advection of velocity and tracer are solved using Edge-based N-scheme which suggest for conservation of mass with tidal flat.

I will say there was no issue regarding mass conservation from the advection term as the FIQU_cfdot=0.0E+0 matched to Cumm. QCST, means when the transport of tracer only consider advection without diffusion.

The keyword that you suggest is TREATMENT OF FLUXES AT THE BOUNDARIES, 1=Priority to prescribed values, 2=Priority to fluxes. I will try the keyword first and will update the finding.

Many thanks,
Amyrhul