velocity BC for inlet and outlet

SimuJo · October 18, 2019, 02:15

Hi there,

I would like to simulate the flow in a closed area. I only have the body (wall) and the two patches for inlet and outlet. Both, inlet and outlet are the same size. In real, inflow and outflow caused by radial fan and have a velocity of about 10m / s. The pressure is not importent for me.

solver: simpleFoam
turbulence model: k-epsilon

Question: How can I set the velocity at the inlet AND outlet? and how do I set the other BC?

So far:
Inlet: U=10 m/s P=zeroGradient
Outlet:U=-10m/s P=fixedValue

Any information would be great.

Cheers

geth03 · June 23, 2020, 08:59

you should never do that,
you can give the inlet velocity and then give a reference pressure at outlet as BC. bc of mass conservation you should automatically have your mass conserved, i.e. average velocity at patch should be as in inlet.
if you give same value at outlet you will not allow a developed profile.

October 18, 2019, 02:15	velocity BC for inlet and outlet	#1
SimuJo New Member Jochen Join Date: Oct 2019 Posts: 3 Rep Power: 6	Hi there, I would like to simulate the flow in a closed area. I only have the body (wall) and the two patches for inlet and outlet. Both, inlet and outlet are the same size. In real, inflow and outflow caused by radial fan and have a velocity of about 10m / s. The pressure is not importent for me. solver: simpleFoam turbulence model: k-epsilon Question: How can I set the velocity at the inlet AND outlet? and how do I set the other BC? So far: Inlet: U=10 m/s P=zeroGradient Outlet:U=-10m/s P=fixedValue Any information would be great. Cheers

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June 23, 2020, 08:59		#2
geth03 Senior Member Join Date: Dec 2019 Location: Cologne, Germany Posts: 355 Rep Power: 8	you should never do that, you can give the inlet velocity and then give a reference pressure at outlet as BC. bc of mass conservation you should automatically have your mass conserved, i.e. average velocity at patch should be as in inlet. if you give same value at outlet you will not allow a developed profile.