Transient flow

kmgraju · July 10, 2011, 02:30

Dear all
My inlet is pulsatile pressure . since the inlet is pulsatile , I would like to introduce average mass flow rate at the outlet.

How to set average mass flow rate at the outlet as boundary condition

Thank you

ghorrocks · July 10, 2011, 06:35

What feature do you have to absorb the pulses? Is it compressible flow? Free surface? FSI?

kmgraju · July 10, 2011, 20:40

Quote:

Originally Posted by ghorrocks

What feature do you have to absorb the pulses? Is it compressible flow? Free surface? FSI?

Dear

the flow is incompressible.I have a plan to do FSI as well . Thank you

ghorrocks · July 11, 2011, 06:30

If you do not know what the average flow rate is then you probably should not use it as a boundary condition. In this case you probably know better what the pressure is, so use a pressure boundary instead.

kmgraju · July 11, 2011, 11:39

Quote:

Originally Posted by ghorrocks

If you do not know what the average flow rate is then you probably should not use it as a boundary condition. In this case you probably know better what the pressure is, so use a pressure boundary instead.

Dear friend

The average flow is the variable at the outlet . so I may vary the flow . If the inlet pressure is pulsatile , The flow is also a pulsatile nature . Am I correct? if this is correct , I want to give average flow over the area . How to set up this boundary condition for this at the outlet ?

Thank you

Regards

Govind

ghorrocks · July 11, 2011, 19:16

If you know the average flow then simply assign the exit to be a flow rate boundary with the average flow.

Be very careful that you have properly specified the boundary conditions. I recommend you read the CFX documentation on boundary condition specification to make sure you are heading in the right direction.

July 10, 2011, 02:30	Transient flow	#1
kmgraju Senior Member Govindaraju Join Date: Apr 2010 Posts: 209 Rep Power: 17	Dear all My inlet is pulsatile pressure . since the inlet is pulsatile , I would like to introduce average mass flow rate at the outlet. How to set average mass flow rate at the outlet as boundary condition Thank you

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July 10, 2011, 06:35		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	What feature do you have to absorb the pulses? Is it compressible flow? Free surface? FSI?

July 11, 2011, 06:30		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	If you do not know what the average flow rate is then you probably should not use it as a boundary condition. In this case you probably know better what the pressure is, so use a pressure boundary instead.

July 11, 2011, 19:16		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	If you know the average flow then simply assign the exit to be a flow rate boundary with the average flow. Be very careful that you have properly specified the boundary conditions. I recommend you read the CFX documentation on boundary condition specification to make sure you are heading in the right direction.