How to increase an AMI timestep size

reidwill · November 6, 2021, 07:03

Hi, I'm a beginner OpenFOAM user utilizing the software for a master's project.

I am using OpenFOAM to model a Rotorod air sampling collector that rotates at 2,400 rpm and when running my model with an adjustable timestep based on the maximum Courant number of 1 it provides a timestep of roughly 7e-6 s. I am aware that the rpm speed is very high which contributes to the low timestep but I need to model a fair amount of seconds to complete a particle tracking study.

Is the best method to increase the timestep size to balance the mesh size that is coarse enough to reduce the Courant number but fine enough that the AMI can operate? Or are there other tricks/methods I've missed?

Any help or suggestions will be appreciated!

Cheers

night-hawk · November 8, 2021, 00:35

You can try MRF method. AMI uses real mesh Motion while MRF uses virtual. MRF is some what faster then AMI.

November 6, 2021, 07:03	How to increase an AMI timestep size	#1
reidwill New Member Reid Join Date: Jun 2021 Location: New Zealand Posts: 3 Rep Power: 4	Hi, I'm a beginner OpenFOAM user utilizing the software for a master's project. I am using OpenFOAM to model a Rotorod air sampling collector that rotates at 2,400 rpm and when running my model with an adjustable timestep based on the maximum Courant number of 1 it provides a timestep of roughly 7e-6 s. I am aware that the rpm speed is very high which contributes to the low timestep but I need to model a fair amount of seconds to complete a particle tracking study. Is the best method to increase the timestep size to balance the mesh size that is coarse enough to reduce the Courant number but fine enough that the AMI can operate? Or are there other tricks/methods I've missed? Any help or suggestions will be appreciated! Cheers

November 8, 2021, 00:35		#2
night-hawk Member Ashutosh Join Date: Jul 2021 Location: India Posts: 75 Rep Power: 4	You can try MRF method. AMI uses real mesh Motion while MRF uses virtual. MRF is some what faster then AMI. reidwill likes this.

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