Total pressure compressible flow

cyril2304 · October 31, 2017, 08:18

hello all,
I am working on scramjet inlet
i want total pressure recovery
so when we calculated total pressure results from fluent and OpenFoam are very different.
rest pressure(static),density,MachNO.velocity matches well.

fluent uses formula
Pt = Po *(1+ (kappa-1)*M^2 /2)^(kappa/kappa-1)

for openFoam i used postProcess utility totalPressureCompressible
results are not matching up
can u guys help

tomf · November 1, 2017, 05:47

That is because OpenFOAM uses:

$p_t=p_{ref}+p+0.5*\rho*U^2$
which should equal the Fluent value only in isentropic flow conditions.

You can find some explanation on the funtionObjects in the cpp source guide

I would suggest to use a ParaView calculator to use the same formulation as Fluent.

Regards,
Tom

October 31, 2017, 08:18	Total pressure compressible flow	#1
cyril2304 New Member cyril dsouza Join Date: Jul 2017 Posts: 3 Rep Power: 9	hello all, I am working on scramjet inlet i want total pressure recovery so when we calculated total pressure results from fluent and OpenFoam are very different. rest pressure(static),density,MachNO.velocity matches well. fluent uses formula Pt = Po (1+ (kappa-1)M^2 /2)^(kappa/kappa-1) for openFoam i used postProcess utility totalPressureCompressible results are not matching up can u guys help

November 1, 2017, 05:47		#2
tomf Senior Member Tom Fahner Join Date: Mar 2009 Location: Breda, Netherlands Posts: 647 Rep Power: 32	That is because OpenFOAM uses: $p_t=p_{ref}+p+0.5\rhoU^2$ which should equal the Fluent value only in isentropic flow conditions. You can find some explanation on the funtionObjects in the cpp source guide I would suggest to use a ParaView calculator to use the same formulation as Fluent. Regards, Tom Last edited by tomf; November 1, 2017 at 05:48. Reason: messed up the order

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