courant number initially very high

ashokmoravaneni · April 19, 2017, 11:41

Hello,
Once at the very beginning of simulation only for first 2 iterations courant number is very very high, after that in the next iterations less than 1 till the end of simulation. Does this high value of courant number at very beginning affect my results severely ?
Thanks,

Ashok.M

p.b · April 20, 2017, 21:53

This totally depends on the type of your simulation (steady/unsteady), boundary conditions, initial field values, ...

For steady simulations, only the result at the end (the converged solution) is important.

For unsteady simulations the Courant number only makes sense if your velocity is not completely zero at the beginning of the simulation, as then your time step size might be way to large. There it might help to limit your time step initially with maxDeltaT in controlDict.

Please try to briefly describe your test case and your simulation and I will try to give you a better answer.

Best, Pascal

April 19, 2017, 11:41	courant number initially very high	#1
ashokmoravaneni Member Ashok Join Date: Feb 2017 Posts: 31 Rep Power: 9	Hello, Once at the very beginning of simulation only for first 2 iterations courant number is very very high, after that in the next iterations less than 1 till the end of simulation. Does this high value of courant number at very beginning affect my results severely ? Thanks, Ashok.M

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April 20, 2017, 21:53		#2
p.b New Member Join Date: Apr 2017 Posts: 9 Rep Power: 9	This totally depends on the type of your simulation (steady/unsteady), boundary conditions, initial field values, ... For steady simulations, only the result at the end (the converged solution) is important. For unsteady simulations the Courant number only makes sense if your velocity is not completely zero at the beginning of the simulation, as then your time step size might be way to large. There it might help to limit your time step initially with maxDeltaT in controlDict. Please try to briefly describe your test case and your simulation and I will try to give you a better answer. Best, Pascal