VAWT using AMI very high courant number or very small time step

biau · April 1, 2013, 15:41

Dear all,

I am trying to set up a simulation for a VAWT in OpenFOAM. I can simulate it well in fluent,but I need more computational power. I am currently trying to use OpenFoam in order to be able to use a cluster. At the moment I am trying to simulate a 2D VAWT inside a wind tunnel, so later i can do a 3D in a much more refined mesh.

My OpenFoam version is 2.1.1

I am currently trying a laminar case using cyclicAMI for my sliding interfaces. But after few times steps, the courant number start to go very very high and then the simulation crashes. If i limit the courant number, it will adjust the time step for something very very small which would take forever to compute.

Any help would be appreciated.

Thank you

case file in following link:

https://www.dropbox.com/sh/bg0kos6qrg6jufq/om0HkZSmtn

hakonbar · April 2, 2013, 06:45

Did you remember to split the baffles between the two cell zones?

I think the command is "createOrSplitBaffles -split -overwrite", but you can find it in the file called "Allrun.pre" in the pimpleDyMFoam/propeller tutorial.

biau · April 2, 2013, 09:13

it seemed to help. Lets see how it goes.

Thank you

April 1, 2013, 15:41	VAWT using AMI very high courant number or very small time step	#1
biau New Member Julio Silveira Join Date: Feb 2013 Location: London Posts: 15 Rep Power: 12	Dear all, I am trying to set up a simulation for a VAWT in OpenFOAM. I can simulate it well in fluent,but I need more computational power. I am currently trying to use OpenFoam in order to be able to use a cluster. At the moment I am trying to simulate a 2D VAWT inside a wind tunnel, so later i can do a 3D in a much more refined mesh. My OpenFoam version is 2.1.1 I am currently trying a laminar case using cyclicAMI for my sliding interfaces. But after few times steps, the courant number start to go very very high and then the simulation crashes. If i limit the courant number, it will adjust the time step for something very very small which would take forever to compute. Any help would be appreciated. Thank you case file in following link: https://www.dropbox.com/sh/bg0kos6qrg6jufq/om0HkZSmtn

April 2, 2013, 09:13	simulation	#3
biau New Member Julio Silveira Join Date: Feb 2013 Location: London Posts: 15 Rep Power: 12	it seemed to help. Lets see how it goes. Thank you

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April 2, 2013, 06:45		#2
hakonbar New Member Håkon Bartnes Line Join Date: Mar 2013 Posts: 27 Rep Power: 13	Did you remember to split the baffles between the two cell zones? I think the command is "createOrSplitBaffles -split -overwrite", but you can find it in the file called "Allrun.pre" in the pimpleDyMFoam/propeller tutorial.