open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello community, best wishes for you.

I am working in a flooding model within a small river that crosses a urban zone. I want to se the behavior of the model in dry conditions. For this purpose I have set the inlet boundary condition with Q + H configuration, and the outlet with free condition (444).

I have set the simulation time of one hour, and up to the 38 minute the calculation was going very well. In that moment both FLUX BOUNDARY registers showed NaN values, although one time step before both registered outlet -9.8 and inlet 10.11.

Also a lot of lines with the same message starts to appear in each time step:
GRACJG (BIEF):EXCEEDING MAXIMUM ITERATIONS: 200 RELATIVE PRECISION: NaN

Could someone help with possible solution?

Best regards

Hello,

As told many times in other posts, if a segmentation fault or a NaN (Not a Number) occurs, you should use a debug configuration with debug options to investigate.
See e.g. the S11.gfortran.debug configuration in the $HOMETEL/configs/systel.edf.cfg configuration file, in particular the flag fflags_debug_gfo for gfortran compiler.
fflags_debug_gfo: -g -Wall -fcheck=all -fbacktrace -fbounds-check -finit-integer=-1 -finit-real=nan -ffpe-trap=invalid,zero,overflow

It will show in which subroutine the issue/nan/segfault occurs, the first suspicious line and may help you to change something in your computation.

Hope this helps,

Chi-Tuan

The problem was solved including in the outlet boundary condition Thompson's method.

Thank you so much