Drag convergence

rednass · August 29, 2014, 05:12

Hello,

I have a question for you guys.
I read something about doing a Richardson extrapolation to get the extrapolated value of the drag coefficient. But I only have the total mesh size and not something like grid spacing.
I have done 6 simulations with mesh size from 1 million to 12 million cells and I have the drag value which is converging to a certain value. At 1 million it is 0.286 and at 12 million it is 0.254 and for example at 3 million it is 0.270.

How can I extrapolate this to get the asymptote value of the drag coefficient?

Thanks in advance!

rednass · September 1, 2014, 04:45

Is there somebody who knows this?

tas38 · September 3, 2014, 09:44

Richardson Extrapolation can be applied to the find the asymptotic value of drag using equivalent cell sizes ( h=(V/N)^(1/3) where h is cell dimension, V is total volume, and N is number of cells).

August 29, 2014, 05:12	Drag convergence	#1
rednass New Member Join Date: Jun 2014 Posts: 6 Rep Power: 11	Hello, I have a question for you guys. I read something about doing a Richardson extrapolation to get the extrapolated value of the drag coefficient. But I only have the total mesh size and not something like grid spacing. I have done 6 simulations with mesh size from 1 million to 12 million cells and I have the drag value which is converging to a certain value. At 1 million it is 0.286 and at 12 million it is 0.254 and for example at 3 million it is 0.270. How can I extrapolate this to get the asymptote value of the drag coefficient? Thanks in advance!

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September 1, 2014, 04:45		#2
rednass New Member Join Date: Jun 2014 Posts: 6 Rep Power: 11	Is there somebody who knows this?

September 3, 2014, 09:44		#3
tas38 Senior Member Troy Snyder Join Date: Jul 2009 Location: Akron, OH Posts: 219 Rep Power: 18	Richardson Extrapolation can be applied to the find the asymptotic value of drag using equivalent cell sizes ( h=(V/N)^(1/3) where h is cell dimension, V is total volume, and N is number of cells).