Velocity Profile at inlet if Mass flow rate BC is given

Struggle_Achieve · January 28, 2016, 02:28

Hello Foamers and Researchers!!
Greetings!

I am quite new to OpenFoam, has been practicing it from last 1 month.
I have a doubt and I would be very grateful if anyone can help me with this.

In a problem I have given flowRateInletVelocity boundary condition at my inlet, specifying mass flow rate. fixedFluxPressure BC is given for pressure at the inlet. I want to know that if we give mass flow rate (or volumetric) BC then how the velocity profile at inlet will be decided? (Parabolic, uniform etc)

Regards,
Prateek.

chegdan · January 28, 2016, 10:31

Prateek,

Seems you have double posted, so I'll answer both quickly to let the admin delete one if they like. Have a look at the code in

Code:

/src/finiteVolume/fields/fvPatchFields/derived/flowRateInletVelocity/flowRateInletVelocityFvPatchVectorField.C

there is a line in the updateCoeffs member function that says

Code:

        // mass flow-rate
        operator==(n*avgU/uniformRho);

This lets us know that it is a uniform velocity profile normal to the patch surface. The code is commented to let you know what is happening and look further in the .H file in the same directory for more guidance.

Struggle_Achieve · January 29, 2016, 03:52

Hello Daniel,

Thanks a lot for the quick reply. I noticed afterwards that I posted this twice. Sorry for the same.

Yes I have seen the code as you mentioned and got what you said.

My deepest gratitude for sorting out my confusion.

Regards,
Prateek.

Bdew8556 · April 14, 2019, 22:03

Hey guys,

Do you know how to set the mass flow rate NOT normal to the boundary?

B

January 28, 2016, 02:28	Velocity Profile at inlet if Mass flow rate BC is given	#1
Struggle_Achieve Member Sing Join Date: Jan 2016 Posts: 30 Rep Power: 10	Hello Foamers and Researchers!! Greetings! I am quite new to OpenFoam, has been practicing it from last 1 month. I have a doubt and I would be very grateful if anyone can help me with this. In a problem I have given flowRateInletVelocity boundary condition at my inlet, specifying mass flow rate. fixedFluxPressure BC is given for pressure at the inlet. I want to know that if we give mass flow rate (or volumetric) BC then how the velocity profile at inlet will be decided? (Parabolic, uniform etc) Regards, Prateek.

January 28, 2016, 10:31		#2
chegdan Senior Member Daniel P. Combest Join Date: Mar 2009 Location: St. Louis, USA Posts: 621 Rep Power: 0	Prateek, Seems you have double posted, so I'll answer both quickly to let the admin delete one if they like. Have a look at the code in Code: /src/finiteVolume/fields/fvPatchFields/derived/flowRateInletVelocity/flowRateInletVelocityFvPatchVectorField.C there is a line in the updateCoeffs member function that says Code: // mass flow-rate operator==(n*avgU/uniformRho); This lets us know that it is a uniform velocity profile normal to the patch surface. The code is commented to let you know what is happening and look further in the .H file in the same directory for more guidance. Struggle_Achieve likes this.

January 29, 2016, 03:52		#3
Struggle_Achieve Member Sing Join Date: Jan 2016 Posts: 30 Rep Power: 10	Hello Daniel, Thanks a lot for the quick reply. I noticed afterwards that I posted this twice. Sorry for the same. Yes I have seen the code as you mentioned and got what you said. My deepest gratitude for sorting out my confusion. Regards, Prateek. chegdan likes this.

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