Bounding omega and k are extreme values during solving

Danmeal · September 6, 2023, 12:50

Hello,

Trying to do a simulation of an Ahmed body to get the drag coefficient. Whilst I've managed to get down to a difference of 15% between the real and simulation values, I've noticed during my simulations that bounding k and omega values are through the roof (bigger than 1e100).

Is this something to be concerned about even though my simulation reports (near) accurate drag coefficients?

sharonyue · September 8, 2023, 02:08

> a difference of 15% between the real and simulation values
> accurate drag coefficients?

Your two statements looks contradictory each other.

Bounding turbulent variables are quite common in OpenFOAM. But thats 1e100 is a bit too large. I remember the mesh quality of Ahmed test case is not very good. If you can make the quality better, I am pretty sure the extremely large value will be seriously decreased.

September 6, 2023, 12:50	Bounding omega and k are extreme values during solving	#1
Danmeal New Member Daniel Join Date: Sep 2023 Posts: 5 Rep Power: 2	Hello, Trying to do a simulation of an Ahmed body to get the drag coefficient. Whilst I've managed to get down to a difference of 15% between the real and simulation values, I've noticed during my simulations that bounding k and omega values are through the roof (bigger than 1e100). Is this something to be concerned about even though my simulation reports (near) accurate drag coefficients?

September 8, 2023, 02:08		#2
sharonyue Senior Member Dongyue Li Join Date: Jun 2012 Location: Beijing, China Posts: 838 Rep Power: 17	> a difference of 15% between the real and simulation values > accurate drag coefficients? Your two statements looks contradictory each other. Bounding turbulent variables are quite common in OpenFOAM. But thats 1e100 is a bit too large. I remember the mesh quality of Ahmed test case is not very good. If you can make the quality better, I am pretty sure the extremely large value will be seriously decreased. __________________ My OpenFOAM algorithm website: http://dyfluid.com By far the largest Chinese CFD-based forum: http://www.cfd-china.com/category/6/openfoam We provide lots of clusters to Chinese customers, and we are considering to do business overseas: http://dyfluid.com/DMCmodel.html

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