how to simulate vortex

raj_yk · March 27, 2009, 01:19

Hi friends,
I am using VOF model of fluent. I have a open(to atmophere) tank in which water level is varying.One inlet and one outlet is present in the bottom of the tank.
Actually at particular level of water there should be vortex formation followed by air entrainment as i see experimently at the outlet of the tank, but this is not happening in fluent.I have tried for different level of water and flow rate but still it is not coming.
so how it can be done, is there any method for making the vortex to be happen at outlet side? Please help me.

thanks in advance.

A_Lyaskin · March 27, 2009, 06:43

As far as I know the underlying mechanism in outlet vortex formation is amplification of initially present vortices by vortex stretching. The initial vortices come either from unsettled disturbances in the tank or from asymmetry (even very small!) of the sink. In your case you're probably just don't have these initial vortices. You can try to introduce very small initial vorticity in your solution

raj_yk · March 27, 2009, 08:46

As you tell i should initial small vortex, so how can i give this condition in fluent.means what are the steps for providing initial votex........
please guide me.
thanks you

A_Lyaskin · March 27, 2009, 12:21

Well, I'm not a Fluent user, so I can give only some general guidelines (you can ask about the details at Fluent forum). The best way is to check the available options concerning flow initialization - is it possible to specify something but zero velocity field? Most probably there is some way to specify initial rotation there. Otherwise you can alter your geometry, especially the sink, making it eee... less axially symmetric

March 27, 2009, 01:19	how to simulate vortex	#1
raj_yk New Member yogesh Join Date: Mar 2009 Posts: 2 Rep Power: 0	Hi friends, I am using VOF model of fluent. I have a open(to atmophere) tank in which water level is varying.One inlet and one outlet is present in the bottom of the tank. Actually at particular level of water there should be vortex formation followed by air entrainment as i see experimently at the outlet of the tank, but this is not happening in fluent.I have tried for different level of water and flow rate but still it is not coming. so how it can be done, is there any method for making the vortex to be happen at outlet side? Please help me. thanks in advance.

March 27, 2009, 08:46	Thank you Anton	#3
raj_yk New Member yogesh Join Date: Mar 2009 Posts: 2 Rep Power: 0	As you tell i should initial small vortex, so how can i give this condition in fluent.means what are the steps for providing initial votex........ please guide me. thanks you

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March 27, 2009, 06:43		#2
A_Lyaskin Member Anton Lyaskin Join Date: Mar 2009 Location: Samara, Russia Posts: 66 Rep Power: 17	As far as I know the underlying mechanism in outlet vortex formation is amplification of initially present vortices by vortex stretching. The initial vortices come either from unsettled disturbances in the tank or from asymmetry (even very small!) of the sink. In your case you're probably just don't have these initial vortices. You can try to introduce very small initial vorticity in your solution

March 27, 2009, 12:21		#4
A_Lyaskin Member Anton Lyaskin Join Date: Mar 2009 Location: Samara, Russia Posts: 66 Rep Power: 17	Well, I'm not a Fluent user, so I can give only some general guidelines (you can ask about the details at Fluent forum). The best way is to check the available options concerning flow initialization - is it possible to specify something but zero velocity field? Most probably there is some way to specify initial rotation there. Otherwise you can alter your geometry, especially the sink, making it eee... less axially symmetric