When to use Pressure outlet bc?

alinik · July 6, 2017, 12:51

Hi All,

I just read in a tutorial online that "pressure outlet" boundary condition must only be used if the inlet BC is "pressure inlet".

Is that true? and why?

Thanks,
Ali

LuckyTran · July 6, 2017, 15:19

No it is not true. In many cases the outlet pressure is the only hard boundary condition that you even have. Maybe you misinterpreted something else. For example, maybe you were reading a pressure outlet with targeted mass-flow rate.

alinik · July 7, 2017, 18:03

Thank you so much.
I read it in the slide#13 of this power point.

https://lyle.smu.edu/me/7337/fluent_bcs.pdf

Do you think it is wrong?

juliom · July 8, 2017, 07:17

That's is easy to answer, if you specify both pressure then the system is over specified. It will diverge. The only way that may work is incompressible flows. However, my experience shows that pressure is always the hardest to get working properly

July 7, 2017, 18:03		#3
alinik Senior Member ali Join Date: Oct 2009 Posts: 318 Rep Power: 17	Thank you so much. I read it in the slide#13 of this power point. https://lyle.smu.edu/me/7337/fluent_bcs.pdf Do you think it is wrong? Last edited by alinik; July 7, 2017 at 18:07. Reason: attachement

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July 6, 2017, 12:51	When to use Pressure outlet bc?	#1
alinik Senior Member ali Join Date: Oct 2009 Posts: 318 Rep Power: 17	Hi All, I just read in a tutorial online that "pressure outlet" boundary condition must only be used if the inlet BC is "pressure inlet". Is that true? and why? Thanks, Ali

July 6, 2017, 15:19		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,668 Rep Power: 65	No it is not true. In many cases the outlet pressure is the only hard boundary condition that you even have. Maybe you misinterpreted something else. For example, maybe you were reading a pressure outlet with targeted mass-flow rate.

July 8, 2017, 07:17		#4
juliom Senior Member Julio Mendez Join Date: Apr 2009 Location: Fairburn, GA. USA Posts: 290 Rep Power: 18	That's is easy to answer, if you specify both pressure then the system is over specified. It will diverge. The only way that may work is incompressible flows. However, my experience shows that pressure is always the hardest to get working properly