Limit cell velocity by threshold

brucethemoose · July 26, 2019, 08:08

Hello,

Is it possible to make apply a different numerical scheme to a certain number of cells within a threshold? For example, if a cell flagged as being above a scalar velocity, say 100m/s, it is then placed in the threshold derived part. Is it then possible to limit the velocity of those cells in the next iteration by applying a different discretization such as first order to those cells only?

For context I am running an incompressible case of a car in a windtunnel with the coupled solver. The geometry has a few very tight gaps that have moving surfaces on either side of the gap, between the rotating wheels and the moving road. This causes the flow there to accelerate far beyond what is physically possible, the solution still runs and converges but I want to limit the effects of this. Changing the geometry or boundary conditions is not possible.

Thanks for any advice,
Bruce

me3840 · July 28, 2019, 14:19

No, there is no functionality for what you're requesting. You could invent a sort of damping source term, but IMO that is not the correct approach to dealing with this; thousands of companies do this simulation every day with no need for such things.

Your best bet is to improve the mesh in that area.

July 26, 2019, 08:08	Limit cell velocity by threshold	#1
brucethemoose New Member Bruce Join Date: Jul 2019 Posts: 1 Rep Power: 0	Hello, Is it possible to make apply a different numerical scheme to a certain number of cells within a threshold? For example, if a cell flagged as being above a scalar velocity, say 100m/s, it is then placed in the threshold derived part. Is it then possible to limit the velocity of those cells in the next iteration by applying a different discretization such as first order to those cells only? For context I am running an incompressible case of a car in a windtunnel with the coupled solver. The geometry has a few very tight gaps that have moving surfaces on either side of the gap, between the rotating wheels and the moving road. This causes the flow there to accelerate far beyond what is physically possible, the solution still runs and converges but I want to limit the effects of this. Changing the geometry or boundary conditions is not possible. Thanks for any advice, Bruce

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July 28, 2019, 14:19		#2
me3840 Senior Member Join Date: Nov 2010 Location: USA Posts: 1,232 Rep Power: 24	No, there is no functionality for what you're requesting. You could invent a sort of damping source term, but IMO that is not the correct approach to dealing with this; thousands of companies do this simulation every day with no need for such things. Your best bet is to improve the mesh in that area.