Simulation time in CFX

Julian121 · July 25, 2019, 08:59

I am running a transient simulation which has a total number of less than 2 m elements and 1.4 m nodes.

I am running it under local parallel processing.

I have tested 8-10-12-16 cores for 100 time steps. Each time step has 5-6 inner iterations.

It takes 150 min to complete 100 time steps under 16 cores.

It takes slightly more time if I use less cores.

I feel the simulation is too slow.

Is it normal for 100 time steps (500-600 iterations) to take 150 mins?

Opaque · July 25, 2019, 09:15

Slow/Fast are relative quantities respect to some reference

May I ask what is your baseline time for "normal speed"?

Then, given the reference, you must also compare settings. One iteration of a tough problem does not cost the same than a simpler problem keeping the same mesh.

One iteration at a large timestep does not the same as the same iteration with a smaller timestep.

Summary: it depends on the problem and the settings.

July 25, 2019, 08:59	Simulation time in CFX	#1
Julian121 Senior Member Join Date: Aug 2012 Posts: 269 Rep Power: 15	I am running a transient simulation which has a total number of less than 2 m elements and 1.4 m nodes. I am running it under local parallel processing. I have tested 8-10-12-16 cores for 100 time steps. Each time step has 5-6 inner iterations. It takes 150 min to complete 100 time steps under 16 cores. It takes slightly more time if I use less cores. I feel the simulation is too slow. Is it normal for 100 time steps (500-600 iterations) to take 150 mins?

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July 25, 2019, 09:15		#2
Opaque Senior Member Join Date: Jun 2009 Posts: 1,869 Rep Power: 33	Slow/Fast are relative quantities respect to some reference May I ask what is your baseline time for "normal speed"? Then, given the reference, you must also compare settings. One iteration of a tough problem does not cost the same than a simpler problem keeping the same mesh. One iteration at a large timestep does not the same as the same iteration with a smaller timestep. Summary: it depends on the problem and the settings.