Calculating mass flow rate at multiphase flows

Kuslo187 · June 5, 2015, 07:10

Hi guys,

I'm new to this forum and I have been searching this forum now for several days. I would be very happy if someone could give me a hint how te solve my problem. Thank you guys in advance! I didn't know where to put this thread, so I opened a knew one.

I want to model the flow through porous media and I use OF 2.3. I am going to describe my task, maybe someone knows how to get along with this.

It is a multiphase flow of water in an air-field which is not moving. The water flows out of a water tap and flows through the air phase to the
ground which is porous. The water flows through and on the porous zone.
The boundary conditions are atmospheric.
The mass flow at the outlet of the porous zone is what interests me the most of course volumetric flow rate would be fine, too.

I post process the results by creating a slice and apply the filter integrate Variables on it. If the magnitude is of interest I calculate it with the calculator. In my understanding the volumetric flow rate which would be the integrate mag(U) should stay constant.

What I have figured out so far is, that the VOF method used in interfoam is insufficient because the velocity field is given for both phases
and not separately for each phase. Without having the velocity for the water jet I can’t calculate the volumetric flow rate. The resulting errors are too big.

Since the solver consolidation of OF 2.2. we can define porosity with every solver and I therefore I tried to use twoPhaseEulerFoam. But this doesn't work yet, because of convergence problems. The simulation crashes pretty soon.

Last but not least I tried a lagrangian solver – Reactingparcelfoam. But I have no idea how post-process the results. I have the particletracks but I can’t evaluate the mass flow through a slice.

Is it possible to calculate the mass flow or volumetric flow rate of the particles (water phase) through a slice? I think this would be the most precise way to solve my problem, but I can't find a tutorial for this.

Does someone have an idea how to solve this problem or is there a way to post-process the results in the needed way?

Thank you for your help in advance!

Christian

wyldckat · August 21, 2015, 19:11

Quick answer: It's a bit late, but you can find the answer for the multiphase mass flow rate here: http://www.cfd-online.com/Forums/ope...tml#post560573 - posts #25 and #26

June 5, 2015, 07:10	Calculating mass flow rate at multiphase flows	#1
Kuslo187 New Member Kuslo Join Date: May 2015 Posts: 2 Rep Power: 0	Hi guys, I'm new to this forum and I have been searching this forum now for several days. I would be very happy if someone could give me a hint how te solve my problem. Thank you guys in advance! I didn't know where to put this thread, so I opened a knew one. I want to model the flow through porous media and I use OF 2.3. I am going to describe my task, maybe someone knows how to get along with this. It is a multiphase flow of water in an air-field which is not moving. The water flows out of a water tap and flows through the air phase to the ground which is porous. The water flows through and on the porous zone. The boundary conditions are atmospheric. The mass flow at the outlet of the porous zone is what interests me the most of course volumetric flow rate would be fine, too. I post process the results by creating a slice and apply the filter integrate Variables on it. If the magnitude is of interest I calculate it with the calculator. In my understanding the volumetric flow rate which would be the integrate mag(U) should stay constant. What I have figured out so far is, that the VOF method used in interfoam is insufficient because the velocity field is given for both phases and not separately for each phase. Without having the velocity for the water jet I can’t calculate the volumetric flow rate. The resulting errors are too big. Since the solver consolidation of OF 2.2. we can define porosity with every solver and I therefore I tried to use twoPhaseEulerFoam. But this doesn't work yet, because of convergence problems. The simulation crashes pretty soon. Last but not least I tried a lagrangian solver – Reactingparcelfoam. But I have no idea how post-process the results. I have the particletracks but I can’t evaluate the mass flow through a slice. Is it possible to calculate the mass flow or volumetric flow rate of the particles (water phase) through a slice? I think this would be the most precise way to solve my problem, but I can't find a tutorial for this. Does someone have an idea how to solve this problem or is there a way to post-process the results in the needed way? Thank you for your help in advance! Christian

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August 21, 2015, 19:11		#2
wyldckat Retired Super Moderator Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,981 Blog Entries: 45 Rep Power: 128	Quick answer: It's a bit late, but you can find the answer for the multiphase mass flow rate here: http://www.cfd-online.com/Forums/ope...tml#post560573 - posts #25 and #26