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Old   February 25, 2013, 17:27
Default Calculating Pressure Drop - BCs
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Hi,

I am trying to simulate flow over an obstruction in a pipe in order to calculate pressure drop across the pipe. I know the flopw rate through the pipe and I also know that nominally the inlet pressure is 100 Pa.

I am not sure how to go about setting up my boundary conditions for this calculation.

At the moment my toughts are:
Pressure:
Inlet - Fixed Value
Outlet - zeroGradient (??)
Walls - zeroGradient

Velocity:
Inlet - fixed value
outlet - inletOutlet with inletValue (0 0 0), not sure what Value option should be here
walls - fixedValue Uniform (0 0 0)

Does this seem correct? I have not done CFD in quite a while now so can't really remember.

I am also wondering the best way to calculate the actual total pressure drop.... Any suggestions here?

Thanks
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Old   February 25, 2013, 19:47
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Nickolas P
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Hello,

Well if you specifiy the pressure and the velocity at the same boundary it is like you re overdefining your problem. As you have a purely pressure driven flow I suggest to specify zero pressure at the exit and flow rate/velocity at the inlet boundary along with no slip at the walls. Since you know the pressure drop as you say, the software then should calculate the flowrate so that to preserve the mass balance.

Regards,

Nickolas
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