neumann boundary condition using UDF

TomatoDuck · October 7, 2014, 08:55

Hi, guys.

how can I impose neumann boundary condition du/dx = 0 (u is velocity component in x-direction) on the boundary highligted with green in the picture?
(The boundary face is normal to x-direction)
Please, HELP!~

Thanks.

macfly · October 9, 2014, 09:35

Outflow boundary condition is what you're looking for, it considers a fully-developed flow in which the flow velocity profile (and/or profiles of other properties such as temperature) is unchanging in the flow direction.

TomatoDuck · October 10, 2014, 04:04

Thank you for your reply, macfly.
Can I ask one more question, please?
Does outflow boundary condition also satisfy v=0(velocity in y direction), w=0(velocity in z direction)?
I mean I have to impose v=0, w=0 as well as du/dx=0 on the boundary.

Thank you.

October 9, 2014, 09:35		#2
macfly Senior Member François Grégoire Join Date: Jan 2010 Location: Canada Posts: 392 Rep Power: 17	Outflow boundary condition is what you're looking for, it considers a fully-developed flow in which the flow velocity profile (and/or profiles of other properties such as temperature) is unchanging in the flow direction. Last edited by macfly; October 9, 2014 at 09:43. Reason: I was wrong.

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October 10, 2014, 04:04		#3
TomatoDuck New Member Yoon, Seung-Hyun Join Date: Oct 2014 Posts: 2 Rep Power: 0	Thank you for your reply, macfly. Can I ask one more question, please? Does outflow boundary condition also satisfy v=0(velocity in y direction), w=0(velocity in z direction)? I mean I have to impose v=0, w=0 as well as du/dx=0 on the boundary. Thank you.