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Old   June 28, 2011, 11:49
Question fluid bc's in turbomachinery
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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:450C

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
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Old   June 29, 2011, 06:30
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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
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