fluid bc's in turbomachinery

rskrishna87 · June 28, 2011, 11:49

Hi everyone,

I have a turbomachinery problem. I n which i have to set the pressure boundary condition at the inlet to a static pressure of 18 atm and at the outlet to 15 atm. Which is typical boundary conditions in turbomachinery. But there is problem in the convergence and it is creating a wall at the outlet in order to prevent the fluid from flowing out of the domain which is not desired and hence there are some convergene problems.

I have given Inlet boundary conditions as:
Static Pressure:18 atm
Flow direction:Normal to boundary condition
turbulence:5%(Medium)
Static Temperature:450°C

Outlet boundary conditions:
Average Static pressure: pressure profile bend=0.05

I am wondering if the flow direction change anything in the results. And are my boundary conditions specified correctly.

Thanks in advance,
Krishna

kambireddy · June 29, 2011, 06:30

I can say, absolutely no. u shld nt use SP(static pressure) at inlet and outlet. Use TP as inlet and SP as outlet. or Q at inlet and SP at outlet(Robust). Go through Cfd Help for clear diff BC`s.

Though u r giving SP on both sides u ll get results which were not realistic. According to u, u had SP information at inlet and outlet. let us take bernoulis eq, in that u will get diff in velocity values after applying ur SP values. bt for absoulte value u need either TP or velocity at any side information.

Hope u got it

June 28, 2011, 11:49	fluid bc's in turbomachinery	#1
rskrishna87 Member Join Date: Jan 2011 Posts: 37 Rep Power: 16	Hi everyone, I have a turbomachinery problem. I n which i have to set the pressure boundary condition at the inlet to a static pressure of 18 atm and at the outlet to 15 atm. Which is typical boundary conditions in turbomachinery. But there is problem in the convergence and it is creating a wall at the outlet in order to prevent the fluid from flowing out of the domain which is not desired and hence there are some convergene problems. I have given Inlet boundary conditions as: Static Pressure:18 atm Flow direction:Normal to boundary condition turbulence:5%(Medium) Static Temperature:450°C Outlet boundary conditions: Average Static pressure: pressure profile bend=0.05 I am wondering if the flow direction change anything in the results. And are my boundary conditions specified correctly. Thanks in advance, Krishna

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Dealing with BC's in OF 1.6	vkrastev	OpenFOAM Running, Solving & CFD	5	September 4, 2012 11:58
BCs in an FSI simulation of a flexble pipe	vivekcfd	OpenFOAM	10	January 8, 2010 04:14
Fluid pairs	fjalil	Main CFD Forum	0	June 10, 2009 13:47
My Revised "Time Vs Energy" Article For Review	Abhi	Main CFD Forum	2	July 9, 2002 09:08
Terrible Mistake In Fluid Dynamics History	Abhi	Main CFD Forum	12	July 8, 2002 09:11

June 29, 2011, 06:30		#2
kambireddy New Member Redddy Join Date: Sep 2010 Posts: 25 Rep Power: 16	I can say, absolutely no. u shld nt use SP(static pressure) at inlet and outlet. Use TP as inlet and SP as outlet. or Q at inlet and SP at outlet(Robust). Go through Cfd Help for clear diff BC`s. Though u r giving SP on both sides u ll get results which were not realistic. According to u, u had SP information at inlet and outlet. let us take bernoulis eq, in that u will get diff in velocity values after applying ur SP values. bt for absoulte value u need either TP or velocity at any side information. Hope u got it