How do I specify the pressure at interior nodes?

cwl6750084 · February 7, 2020, 23:33

Does anyone knows how can I specify (fix) the pressures at the red boundary of the attached domain? I tried modelling just the C-D nozzle part, however, there are back flows at the outlet and something weird at the inlet. I have to attached the two zones outside the inlet and outlet. Yet, I am not sure how to specify the pressure at the now interior boundaries.

By the way, when using mass flow inlet boundary condition in an axisymmetric problem, should the mass flow rate specified be the complete one or I should only do half of it actual amount?

Thanks for any thoughts.

LuckyTran · February 8, 2020, 16:43

Boundary conditions are applied to boundaries, not interiors. If you can't get the C-D to work, well then that's its own problem.

You specify the mass flow through the entire 2pi radian.

vinerm · February 9, 2020, 15:27

If the domain that you have shared the image of is complete, then it is too small and the flow reversal is expected. Right after the exit and before the inlet of the nozzle, there is sudden expansion and contraction, resp. You need to extend your model is both directions, i.e., upstream as well as downstream. Upstream, it should at least be 4 time the radius of the domain and downstream it should at least be 8 times.

February 9, 2020, 15:27	Too small domain	#3
vinerm Senior Member Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 35	If the domain that you have shared the image of is complete, then it is too small and the flow reversal is expected. Right after the exit and before the inlet of the nozzle, there is sudden expansion and contraction, resp. You need to extend your model is both directions, i.e., upstream as well as downstream. Upstream, it should at least be 4 time the radius of the domain and downstream it should at least be 8 times. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

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February 8, 2020, 16:43		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,679 Rep Power: 66	Boundary conditions are applied to boundaries, not interiors. If you can't get the C-D to work, well then that's its own problem. You specify the mass flow through the entire 2pi radian.