Inlet and Outlet conditions for a nozzle

shastry123 · February 23, 2018, 11:56

I chose velocity inlet condition(inlet velocity being 13.95 m/sec) for subsonic incompressible flow through a nozzle, and outflow condition at the outlet but the solution gives me a very high value(3e5 pascal) at the inlet and a very low value at the outlet (-23000 pascal). Can u suggest me any changes that I have to make to this?

LuckyTran · February 28, 2018, 19:23

If your setup is incompressible then there is no meaning to subsonic. So is your working fluid compressible or no?

Check your mass-flow rate. Try a pressure outlet. Do your velocities make sense so far? What types of values are you expecting for the pressure difference? Maybe you have completely messed up a BC somewhere.

shastry123 · March 1, 2018, 01:04

The fluid is incompressible, it is liquefied wax. The velocity of it should be less than 6m/sec.

[URL="https://drive.google.com/open?id=1wO2K0VXAwBIB7mfvBsvr3eQtPzZ1D_uq"]
I am posting the url(only which is inside the quotations) of the image.

I have named the inlet, outlet for the nozzle as shown in the image file. The plate is subjected to transient force because of which the liquid that is entering through the inlet is forced to the outlet. This is my idea which I want to simulate.

The outlet is exposed to the atmosphere. As I want the liquid to come out of the nozzle, the pressure at outlet should be slightly higher than that of the atmospheric pressure.

February 23, 2018, 11:56	Inlet and Outlet conditions for a nozzle	#1
shastry123 New Member Karnataka Join Date: Feb 2018 Posts: 2 Rep Power: 0	I chose velocity inlet condition(inlet velocity being 13.95 m/sec) for subsonic incompressible flow through a nozzle, and outflow condition at the outlet but the solution gives me a very high value(3e5 pascal) at the inlet and a very low value at the outlet (-23000 pascal). Can u suggest me any changes that I have to make to this?

March 1, 2018, 01:04	Need help with the boundary conditions	#3
shastry123 New Member Karnataka Join Date: Feb 2018 Posts: 2 Rep Power: 0	The fluid is incompressible, it is liquefied wax. The velocity of it should be less than 6m/sec. [URL="https://drive.google.com/open?id=1wO2K0VXAwBIB7mfvBsvr3eQtPzZ1D_uq"] I am posting the url(only which is inside the quotations) of the image. I have named the inlet, outlet for the nozzle as shown in the image file. The plate is subjected to transient force because of which the liquid that is entering through the inlet is forced to the outlet. This is my idea which I want to simulate. The outlet is exposed to the atmosphere. As I want the liquid to come out of the nozzle, the pressure at outlet should be slightly higher than that of the atmospheric pressure.

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February 28, 2018, 19:23		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,761 Rep Power: 66	If your setup is incompressible then there is no meaning to subsonic. So is your working fluid compressible or no? Check your mass-flow rate. Try a pressure outlet. Do your velocities make sense so far? What types of values are you expecting for the pressure difference? Maybe you have completely messed up a BC somewhere.