Simulation of a jet-pump- it does not suck;)

Schurl · January 8, 2018, 07:35

Hello,

i would appreciate some advice regarding the simulation of a jet-pump, see attachment.

As a first step i just used a 2D mesh to check if it works in principle - i am quite new in openFoam btw.
I also used different solvers from icoFoam, compressible solvers etc.
As i also want to check supersonic inlets in future and the jet-inlet-velocity is already quite high I actually use sonicFoam.

But, whatever solver I use and whatever angular value I use für the jet-inlet velocity (45° as sketched or in parallel to the walls towards the outlet) i get no solution, where air is sucked in at the inlet.

The air is always leaving the domain at both sides inlet/outlet, of course much higher at the outlet, but unfortunately it does not suck air in.

Has someone already an idea, if i did a principal mistake here?

Thanks in Advance
George

Taataa · January 8, 2018, 15:43

What boundary conditions have you applied?

Schurl · January 8, 2018, 17:59

Hi,

thanks for your reply.
Please find them enclosed.

KR
George

Files#1 of Case

Schurl · January 8, 2018, 18:01

Files#2 of Case

Schurl · January 8, 2018, 18:04

Files#3 of Case

Schurl · January 8, 2018, 18:15

Oh jesus...it is the InletOutlet BC with fixed flow, or?

Taataa · January 8, 2018, 19:15

You cannot prescribe both pressure and velocity. For inlets either set U as fixedvalue and p as zeroGradient or set p fixedValue and U as pressureInletOutletVelocity.

Schurl · January 8, 2018, 20:08

Thanks! i did a copy&paste error.

Aswell es the initial flow condition was still 650m/s from the tutorial, which i changed to 0m/s.

Now it runs awesome. It takes about 4ms where it starts to suck.
Currently i am at 8ms, where i already have an inlet of 5 m/s.

Kind regards
George

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January 8, 2018, 15:43		#2
Taataa Senior Member Taher Chegini Join Date: Nov 2014 Location: Houston, Texas Posts: 125 Rep Power: 12	What boundary conditions have you applied? Last edited by Taataa; January 8, 2018 at 19:01.

January 8, 2018, 18:15		#6
Schurl New Member Georg Join Date: Dec 2017 Posts: 15 Rep Power: 8	Oh jesus...it is the InletOutlet BC with fixed flow, or?

January 8, 2018, 19:15		#7
Taataa Senior Member Taher Chegini Join Date: Nov 2014 Location: Houston, Texas Posts: 125 Rep Power: 12	You cannot prescribe both pressure and velocity. For inlets either set U as fixedvalue and p as zeroGradient or set p fixedValue and U as pressureInletOutletVelocity.

January 8, 2018, 20:08		#8
Schurl New Member Georg Join Date: Dec 2017 Posts: 15 Rep Power: 8	Thanks! i did a copy&paste error. Aswell es the initial flow condition was still 650m/s from the tutorial, which i changed to 0m/s. Now it runs awesome. It takes about 4ms where it starts to suck. Currently i am at 8ms, where i already have an inlet of 5 m/s. Kind regards George