Boundary Conditions Intlet/Outlet Total Pressure

srnco · June 13, 2014, 08:41

Hello everyone,

I'm calculating some blades and cavitation for a pump.
In a first step I kept the mass flow rate at the same level at the outlet and varied the total pressure at the inlet.

Now I want to vary the mass flow of the pump.
I cant select total pressure at the outlet which also makes sense because the total pressure will surely increase.

At the inlet I have to choose mass flow OR total pressure.

What is the best way to keep the total pressure at 101325 Pa and vary the mass flow of the pump?

Maybe I'm just missing something.

Thanks in advance!

ghorrocks · June 13, 2014, 17:33

You specify boundary conditions to match the known conditions. You do not say where you know the 101325Pa exists.

If the total pressure at the inlet is 101325Pa then put a pressure boundary there and use a mass flow boundary on the outlet.

If the total pressure at the outlet is 101325Pa then put a pressure boundary there and use a mass flow boundary on the inlet.

June 13, 2014, 08:41	Boundary Conditions Intlet/Outlet Total Pressure	#1
srnco New Member Soeren Join Date: Jun 2014 Posts: 1 Rep Power: 0	Hello everyone, I'm calculating some blades and cavitation for a pump. In a first step I kept the mass flow rate at the same level at the outlet and varied the total pressure at the inlet. Now I want to vary the mass flow of the pump. I cant select total pressure at the outlet which also makes sense because the total pressure will surely increase. At the inlet I have to choose mass flow OR total pressure. What is the best way to keep the total pressure at 101325 Pa and vary the mass flow of the pump? Maybe I'm just missing something. Thanks in advance!

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June 13, 2014, 17:33		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	You specify boundary conditions to match the known conditions. You do not say where you know the 101325Pa exists. If the total pressure at the inlet is 101325Pa then put a pressure boundary there and use a mass flow boundary on the outlet. If the total pressure at the outlet is 101325Pa then put a pressure boundary there and use a mass flow boundary on the inlet.