Total time for the transient - rotor stator simulation

saisanthoshm88 · October 28, 2012, 12:38

I'd like to run a transient rotor stator simulation of a cooling fan and I'm applying a time step based on the rpm of the fan and the mesh size on the transient rotor stator interface such that the courant number would be some thing between 1 to 3.

Could some one please let me know how to choose the total time required for the simulation.

ghorrocks · October 28, 2012, 16:13

First of all, your time step selection is wrong (or at least not optimal). You should select a time step to give you 3-5 coeff loops per time step. You can then use adaptive time steps to home in on this criteria and it will automatically find the correct time step size regardless of mesh, speed, flow, convergence criteria or anything else.

The total time required depends on what you want out of this model. If you want the steady state performance then you need to run it long enough to achieve a steady state. Best simply watch the parameters during a run and stop it when it is adequately converged. So set the run up with a massively long total time, and manually stop it when you are happy with it.

October 28, 2012, 12:38	Total time for the transient - rotor stator simulation	#1
saisanthoshm88 Senior Member --------- Join Date: Oct 2010 Posts: 303 Rep Power: 17	I'd like to run a transient rotor stator simulation of a cooling fan and I'm applying a time step based on the rpm of the fan and the mesh size on the transient rotor stator interface such that the courant number would be some thing between 1 to 3. Could some one please let me know how to choose the total time required for the simulation. __________________ Best regards, Santhosh.

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October 28, 2012, 16:13		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	First of all, your time step selection is wrong (or at least not optimal). You should select a time step to give you 3-5 coeff loops per time step. You can then use adaptive time steps to home in on this criteria and it will automatically find the correct time step size regardless of mesh, speed, flow, convergence criteria or anything else. The total time required depends on what you want out of this model. If you want the steady state performance then you need to run it long enough to achieve a steady state. Best simply watch the parameters during a run and stop it when it is adequately converged. So set the run up with a massively long total time, and manually stop it when you are happy with it.