Vortex Rings Generated from low Re sphere

ABF31330 · August 9, 2017, 18:29

Hi all,
I am trying to model a 1um sphere with water flowing past it inside of a box, generating an Re of ~20. I would like to visualize the vortex rings that form as the fluid passes along the sphere. How would I go about structuring the simulation so that this can be measured?

-Adam

LuckyTran · August 10, 2017, 12:08

There's no difference in the way you would run the simulation. At the end of the day, you get velocity at many (or every) time-step and you somehow must use this to visualize the vortex rings.

Unfortunately, flow visualization is not so straightforward. There's many different ways to do this, and I highly recommend doing your own lit search. Some people use isosurfaces of pressure, some use isosurfaces of vorticity, some use Q-criterion, some use lambda-2 criterion, some find complex eigenvalues, and so on and so on.

The issue is that it's hard to come up with a precise definition of a vortex ring that everybody agrees to.

August 9, 2017, 18:29	Vortex Rings Generated from low Re sphere	#1
ABF31330 New Member Adam Freund Join Date: Mar 2017 Posts: 13 Rep Power: 9	Hi all, I am trying to model a 1um sphere with water flowing past it inside of a box, generating an Re of ~20. I would like to visualize the vortex rings that form as the fluid passes along the sphere. How would I go about structuring the simulation so that this can be measured? -Adam

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August 10, 2017, 12:08		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,761 Rep Power: 66	There's no difference in the way you would run the simulation. At the end of the day, you get velocity at many (or every) time-step and you somehow must use this to visualize the vortex rings. Unfortunately, flow visualization is not so straightforward. There's many different ways to do this, and I highly recommend doing your own lit search. Some people use isosurfaces of pressure, some use isosurfaces of vorticity, some use Q-criterion, some use lambda-2 criterion, some find complex eigenvalues, and so on and so on. The issue is that it's hard to come up with a precise definition of a vortex ring that everybody agrees to.