Force library

pechwang · May 22, 2013, 10:05

Hello everyone,

I'm new to OpenFOAM. I played with icoFoam and simpleFoam for a few months. Now I want to move to multi-phase flow, which is mixture of air and water, so I choose interFoam. Then comes the question.
Originally I use the force library to calculate the torque and use patchIntegrate to calculate the volume flow rate in icoFoam and simpleFoam. And the viscosity of the single-phase flow is defined in transportProperties file. But now, it becomes multi-phase flow and the viscosity is a function of the phae fraction of the mixture, and the phase fraction is different everywhere. Then how can I calculate the "local viscosity" to calculate the force and torque on the wall? And how can I calculate the "pure" water flow rate at the boundaries.

Thanks,
Pengchuan

haakon · May 22, 2013, 10:10

When it comes to calculating what you call the "pure water flow" (or the volume flux of one phase only) I think you should study these tutorials:

https://www.hpc.ntnu.no/display/hpc/...llway+Tutorial
https://www.hpc.ntnu.no/display/hpc/...AM+-+swak4Foam

They describe in detail how to monitor flow of one phase, either in the domain or at a boundary.

pechwang · May 22, 2013, 10:20

Hi Hakon,

Thank you for your quick reply, I'll work on that. Thanks again. Then do you have any idea on how to calculate the torque?

Quote:

Originally Posted by haakon

When it comes to calculating what you call the "pure water flow" (or the volume flux of one phase only) I think you should study these tutorials:

https://www.hpc.ntnu.no/display/hpc/...llway+Tutorial
https://www.hpc.ntnu.no/display/hpc/...AM+-+swak4Foam

They describe in detail how to monitor flow of one phase, either in the domain or at a boundary.

haakon · May 22, 2013, 10:28

No, not in multiphase flows at least. I know that in regular, single-phase flows the torque is calculated by the forces and forceCoeffs function objects. You specify the axis around which to calculate the torque with the CofR vector. But again, I am very uncertain on how to do this for multiphase flows.

HanSolo123 · December 24, 2015, 07:33

Hi Pengchuan,

have you made any progress in this problem? I also deal with the problem how to calculate the torque of a patch when there is a multiphase flow and the properties like density and viscosity depend on the alpha value.

Greetings.

May 22, 2013, 10:05	Force library	#1
pechwang Member Pengchuan Wang Join Date: Nov 2012 Location: Michigan USA Posts: 58 Rep Power: 14	Hello everyone, I'm new to OpenFOAM. I played with icoFoam and simpleFoam for a few months. Now I want to move to multi-phase flow, which is mixture of air and water, so I choose interFoam. Then comes the question. Originally I use the force library to calculate the torque and use patchIntegrate to calculate the volume flow rate in icoFoam and simpleFoam. And the viscosity of the single-phase flow is defined in transportProperties file. But now, it becomes multi-phase flow and the viscosity is a function of the phae fraction of the mixture, and the phase fraction is different everywhere. Then how can I calculate the "local viscosity" to calculate the force and torque on the wall? And how can I calculate the "pure" water flow rate at the boundaries. Thanks, Pengchuan

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May 22, 2013, 10:10		#2
haakon Senior Member Join Date: Dec 2011 Posts: 111 Rep Power: 20	When it comes to calculating what you call the "pure water flow" (or the volume flux of one phase only) I think you should study these tutorials: https://www.hpc.ntnu.no/display/hpc/...llway+Tutorial https://www.hpc.ntnu.no/display/hpc/...AM+-+swak4Foam They describe in detail how to monitor flow of one phase, either in the domain or at a boundary.

May 22, 2013, 10:28		#4
haakon Senior Member Join Date: Dec 2011 Posts: 111 Rep Power: 20	No, not in multiphase flows at least. I know that in regular, single-phase flows the torque is calculated by the forces and forceCoeffs function objects. You specify the axis around which to calculate the torque with the CofR vector. But again, I am very uncertain on how to do this for multiphase flows.

December 24, 2015, 07:33		#5
HanSolo123 New Member Hans Barósz Join Date: May 2014 Posts: 22 Rep Power: 12	Hi Pengchuan, have you made any progress in this problem? I also deal with the problem how to calculate the torque of a patch when there is a multiphase flow and the properties like density and viscosity depend on the alpha value. Greetings.