Learning Forum

[oll5hbdfk]

Hello everyone,

the title is the question.

Depending on what I choose in fluent under Setup-General and Solution-Methods, fluent may ask for a Courant-Number or a Flow-Courant-Number. Additionally in the documentation I find the term CFL-Number (e.g. Fluent 2021R1 Theory Guide 28.4.4.2 Under-Relaxation of Equations). Do these terms mean the same thing? I know that they are closely related, but are there small but decisive differences or do they mean exactly the same?

[SRP]

 

Hi,

CFL-Number, Courant Number, and Flow-Courant-Number are all interchangeable words.

Thank you

 

[DrAmine]

Yes.

[DrAmine]

The CFL number used for the Coupled Solver is however something totally different: you should rather interpret it as a sort of under-relaxation has nothing to do with temporal evolution or discreization rather to make matrix more diagonally dominated.

[oll5hbdfk]

OK, so the CFL number when using coupled means something different than the CFL number when using a segregated solver. But "coupled CFL" and "coupled Courant number" is the same. Do I get this right?

[DrAmine]

The CFL number used as Numerical Method Input has nothing to do with real temporal discretization and time evolution of the solution.