Problem of Boundary condition

dahu007 · December 18, 2009, 19:31

I would like to see the flow in a unsteady cylinder. The flux is unsteady and I wrote an UDF to the velocity inlet. The velocity varies from 0m.S to 10m.s. What condition have I to put at the end of the cilinder. If I put pressure outlet, I find that the velocity is the same in all the cylinder and it seems strange, isn't it ? Otherwise, can you explain why the velocity is the same at the begining of the cylinder and at the end ?
Thank you !

dahu007 · December 22, 2009, 19:54

Does anybody have an idéa ???

herntan · December 22, 2009, 20:12

How u setup ur BC for various velocity according to time?

I think ur fluid is imcompressible, so there is no velocity difference in cylinder.
Try change the fluid become Ideal gas.

December 18, 2009, 19:31	Problem of Boundary condition	#1
dahu007 New Member matth Join Date: Aug 2009 Posts: 8 Rep Power: 16	I would like to see the flow in a unsteady cylinder. The flux is unsteady and I wrote an UDF to the velocity inlet. The velocity varies from 0m.S to 10m.s. What condition have I to put at the end of the cilinder. If I put pressure outlet, I find that the velocity is the same in all the cylinder and it seems strange, isn't it ? Otherwise, can you explain why the velocity is the same at the begining of the cylinder and at the end ? Thank you !

December 22, 2009, 20:12		#3
herntan Senior Member YH Tan Join Date: Mar 2009 Location: Malaysia Posts: 119 Rep Power: 17	How u setup ur BC for various velocity according to time? I think ur fluid is imcompressible, so there is no velocity difference in cylinder. Try change the fluid become Ideal gas. __________________ Herntan, Add Reputation if I am right

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December 22, 2009, 19:54		#2
dahu007 New Member matth Join Date: Aug 2009 Posts: 8 Rep Power: 16	Does anybody have an idéa ???