# Adjusting the time step dynamically in OpenFOAM?

I'm experimenting with OpenFOAM. In my simulation of a time-dependent, transitional flow the Courant number remains well below 1 for a certain period but then rises, eventually leading to a floating point exception. In order to avoid it, I reduced the time step, with the consequence of an unacceptable slowdown of the simulation. Is there a possibility of dynamically adjusting the time step in dependence of the Courant number?

• Which solver are you using? And are you using OpenFOAM-2.1?
– akid
Sep 3, 2012 at 7:57
• What @akid is saying: there ARE solvers in OpenFOAM that adjust the time-step. But not all Sep 3, 2012 at 8:33
• @akid: I'm using OpenFOAM-2.1 with the PIMPLE solver. Is there any other suitable for my problem (incompressible, transient, time-dependent flow)? Sep 3, 2012 at 13:36
• @Igor transient and time-dependent is the same thing
– akid
Sep 3, 2012 at 15:47
• @akid Sorry, I meant "transitional". Sep 3, 2012 at 20:16

• Side-note from here: "For future reference, pimpleFoam can be run essentially as pisoFoam by setting nOuterCorrectors to 1. This alleviates any coding problem. pimpleFoam supports adjustable timestep." Feb 18, 2020 at 9:06