Compilation error in a code

Dear All,
I am trying to compile a code for non dimensional equation and unfortunately I am getting error (mentioned below):

it seems some value of variable is large that could not be operated within the freefem.

kindly suggest !!!

You use the convect operator with a to high velocity or a velocity with a NaN value, so the method do not works.

remark, in convect operator statically the pass trough n triangle/element where n is more or less
n = velocity/ meshsize and for the method n must be less than 10, and here n > 1000

best regards,

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Dear Sir,
Thanks It helped me a lot.
One, more doubt I have. It would help me further to code system of PDE.

  • if we have four governing Eq (PDE) for a model then separately they need to formulate as a problem.


problem1(…) = First weak form equation.
problem2(…) = Second weak form equation.
problem3(…) = Third β€œβ€ β€œβ€
problem4(…) = Fourth β€œβ€" β€œβ€"

after that we can solve it separately.

Am I proceeding in the right direction or only a single equation can deal with the problem.

Kindly suggest something.


It all depends on the coupling you want to impose between your governing equations. What you describe is usually called weak coupling. If you use a single problem with all governing equations inside, it is usually called strong coupling. What you propose should work fine if your problem is not too stiff.

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Thanks @prj,
It clarify my doubts regarding defining my problems.

One more point, I am not getting for the stiff nature of problem address by you.

Stiff addresses complexity of the problem or computational cost?

Very crudely, the stiffness of the system quantifies how each problem is connected with the others.

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Thanks @prj
now it become easy for me to understand and code a problem in freefem.