pressure far field boundary condition

hussein93 · July 7, 2022, 05:16

Hey, I am investigating the flow in a turbine with only one stator. For the outlet I would like to set a pressure far field BC, because I don't now the static pressure in the outlet. For this I have extended my domain length by 20 times the chord length of the blade. So how can I set this BC, with external for the outlet ? Sam using Omnis v2,
thx

colinda1 · July 18, 2022, 08:19

Hi,

For an external boundary condition knowledge on the pressure, temperature and velocity is still needed. So this is really mostly useful in far field conditions like the far field far away from an aircraft or a car for example: then the pressure and temperature and velocity direction are known if it is really far from the region of interest and flow field gradients are negligible.

An outlet pressure boundary condition would probably be better in this case.

gsgt07 · August 11, 2022, 07:35

Hi,
As in such type of cases the time marching boundary condition are used i.e. convective boundary condition and if you don't know the outside pressure in that case pressure gradient BC are implemented i.e. dp/dn = 0;

Bdew8556 · November 6, 2022, 19:15

What exactly is Fluent setting with the Pressure Far Field Boundary Condition? I'm having trouble finding anything definitive. I'm also noting it does not seem to like lower mach numbers. Any thoughts/equations would be fantastic.

July 7, 2022, 05:16	pressure far field boundary condition	#1
hussein93 New Member Join Date: Apr 2022 Posts: 10 Rep Power: 4	Hey, I am investigating the flow in a turbine with only one stator. For the outlet I would like to set a pressure far field BC, because I don't now the static pressure in the outlet. For this I have extended my domain length by 20 times the chord length of the blade. So how can I set this BC, with external for the outlet ? Sam using Omnis v2, thx

July 18, 2022, 08:19	Outlet pressure boundary condition	#2
colinda1 Senior Member Colinda Join Date: May 2012 Location: Brussels Posts: 153 Rep Power: 14	Hi, For an external boundary condition knowledge on the pressure, temperature and velocity is still needed. So this is really mostly useful in far field conditions like the far field far away from an aircraft or a car for example: then the pressure and temperature and velocity direction are known if it is really far from the region of interest and flow field gradients are negligible. An outlet pressure boundary condition would probably be better in this case.

November 6, 2022, 19:15	reply	#4
Bdew8556 Senior Member Brett Join Date: May 2013 Posts: 212 Rep Power: 14	What exactly is Fluent setting with the Pressure Far Field Boundary Condition? I'm having trouble finding anything definitive. I'm also noting it does not seem to like lower mach numbers. Any thoughts/equations would be fantastic. colinda1 likes this.

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August 11, 2022, 07:35		#3
gsgt07 New Member Join Date: Aug 2022 Posts: 7 Rep Power: 4	Hi, As in such type of cases the time marching boundary condition are used i.e. convective boundary condition and if you don't know the outside pressure in that case pressure gradient BC are implemented i.e. dp/dn = 0;