CFL number in Post-processing

HI everyone,

I want to investigate the effect of timestep size based on CFL number (from 0.5 - 10). May i know where can i get the value of CFL during post processing? I only found "CFL timeInc" in the log file but i dont think this is the CFL value. I am expecting to see average, min and max CFL.

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AcuSolve

HyperMesh CFD

v2023.1

Accepted answers

acupro

I don't recall what was or was not in AcuFieldView (AcuFV) - as that was some years back now. There was no functionality removed from the AcuSolve/solver side - but if CFL was available in AcuFV maybe there was something in AcuFV (licensed from other provider) itself that made the CFL calculation possible.

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acupro

I'm not aware of a method to calculate CFL on a global scale for AcuSolve. (The CFL Time Increment in the Log file is an estimate of the time increment needed to give CFL 1 or lower everywhere.) I note that for the vast majority of cases in AcuSolve the CFL does not limit the stability of the solver. The time increment affects the accuracy of solution, but generally not the stability of the solver.

acupro

There may be a way. If you enable Derived Quantity Output at the same frequency as Nodal Output - this may give you cfl_number as part of extended nodal output. Once you've run you can try with:

acuTrans -pb <problem_name> -out -extout -to stats -outv cfl_number

If that give you results (min/max/average) then you should also have access to that for Post, so long as you use/translate extended output variables.

Rookie_CFD

hmmmm… thanks for the info. However, if i am not mistaken, during AcuConsole, the CFL number is available by default in AcuFieldView right? Why not retain it in Hypermesh CFD? Much more easier that way for the user.

acupro