Stratified Two-Phase Flow

alberto · May 26, 2010, 01:15

Sorry, ignore the comment on cavitatingFoam. I was actually referring to interPhaseChangeFoam, which is a VOF code with mass-transfer.

sabin.ceuca · May 26, 2010, 05:43

Hi guys, I am also working on the simulation of 2-phase stratified flow with OpenFOAM. I would recommend to you “Metro”, that you don’t start the simulation with the full “steam” velocity of 10m/s but using a ramp starting from u_steam = u_water. I have experienced a lot of crashes if not preceding so.
Greatings Sabin

metro · May 30, 2010, 01:19

Hey

I have been experimenting with the twoPhaseEulerFoam and been applying it to a 10inch pipe with non uniform B.C to determine its accuracy. The conditions were applied with funkySetFields and groovyBC and are piecewise functions for simplicity

. Ive also filled half of the control volume with liquid to help with convergence. The problem which I am encountering is that the system isn't converging and my Courant number exceeds the limits set in the control dict

. Any help will be greatly appreciated.............

(PS Ive already increased the maxdeltaT and changed the U values but no use)

Thanks

Metro

alberto · May 30, 2010, 02:17

Change one condition at a time to understand what is causing the problem.

You should reduce the maxDeltaT if you have that kind of problem, not increase it :-)

metro · May 30, 2010, 18:01

Hey Alberto,

I have done the following -

1) decrease the maxdeltaT to 1e-7 (My mistake in the previous thread

)

2) changed the velocities to more realistic figures (1 and 10m/s for liquid and gas)

3) set the internalfield for both the alpha and the velocities (done with funkysetfields and checked in paraView)

4) checked the pressure boundary conditions

And it is still not working, Do you have any ideas? Im stuck and realy need some help. Also does anyone have the details on the interPhaseChangeFoam tutorial and the governing equations?

Thanks

Metro

sabin.ceuca · June 4, 2010, 08:02

@Metro can you post your input files? Ok, I am not an advanced user of OF but maybe I can help

Greats

metro · June 11, 2010, 01:09

Thanks for the input. I found that I set the phase interfacial properties incorrectly and as a result it affected the convergence. It seems to be working now.

I am currently looking into incorporating a temperature field into the twoPhaseEulerFoam solver. Is there any one who has done this and might be able to assist.

Thanks Metro

sabin.ceuca · June 11, 2010, 04:58

There are 2 tutorials, take a look at them http://openfoamwiki.net/index.php/Ho...ure_to_icoFoam
and
http://www.cfd-online.com/Forums/ope...interfoam.html

alberto · June 11, 2010, 14:46

Quote:

Originally Posted by metro

I am currently looking into incorporating a temperature field into the twoPhaseEulerFoam solver. Is there any one who has done this and might be able to assist.

How do you plan to do this? Meaning, how does your energy equation look like?

Best,
A.

jignesh_thaker2007 · January 19, 2012, 04:20

i m started to solve the problem of two phase pipe flow using interDyMFoam solver in which two liquid water and air flowing inside the pipe.but both have different velocities so how can i take care of the boundary condition at inlet?
at the inlet of the pipe the half portion carries water and another half portion carries air but how can i define B.C.?

please help me.

sabin.ceuca · January 19, 2012, 06:56

Hi Jignesh,
the solution to your problem is to split your inlet patch in two parts:
one for the air inflow the other for the water inlet. If you don't want to remesh your domain, as required in order to split a patch, you can use swak4Foam or groovyBC (just google for them). They help you to define a BC as an expersion of, in your case, (x,y,z).
Good luck

jignesh_thaker2007 · January 21, 2012, 01:14

Actually i drew geometry in Gambit and i split inlet in two parts in gambit. then i convert this geometry in openFoam also i put all condition related about that plz check this problem is it right or roungh? so plz give me your mail Id so i will send it to you.

thanks
Jignesh

Quote:

Originally Posted by sabin.ceuca

Hi Jignesh,
the solution to your problem is to split your inlet patch in two parts:
one for the air inflow the other for the water inlet. If you don't want to remesh your domain, as required in order to split a patch, you can use swak4Foam or groovyBC (just google for them). They help you to define a BC as an expersion of, in your case, (x,y,z).
Good luck

May 26, 2010, 01:15		#21
alberto Senior Member Alberto Passalacqua Join Date: Mar 2009 Location: Ames, Iowa, United States Posts: 1,912 Rep Power: 36	Sorry, ignore the comment on cavitatingFoam. I was actually referring to interPhaseChangeFoam, which is a VOF code with mass-transfer. __________________ Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using.

May 30, 2010, 01:19		#23
metro New Member Join Date: May 2010 Posts: 27 Rep Power: 15	Hey I have been experimenting with the twoPhaseEulerFoam and been applying it to a 10inch pipe with non uniform B.C to determine its accuracy. The conditions were applied with funkySetFields and groovyBC and are piecewise functions for simplicity. Ive also filled half of the control volume with liquid to help with convergence. The problem which I am encountering is that the system isn't converging and my Courant number exceeds the limits set in the control dict. Any help will be greatly appreciated............. (PS Ive already increased the maxdeltaT and changed the U values but no use) Thanks Metro Last edited by metro; May 31, 2010 at 04:06.

May 30, 2010, 02:17		#24
alberto Senior Member Alberto Passalacqua Join Date: Mar 2009 Location: Ames, Iowa, United States Posts: 1,912 Rep Power: 36	Change one condition at a time to understand what is causing the problem. You should reduce the maxDeltaT if you have that kind of problem, not increase it :-) __________________ Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using.

January 19, 2012, 04:20	hello sir,	#30
jignesh_thaker2007 Member Jignesh Join Date: Aug 2011 Location: India Posts: 68 Rep Power: 14	i m started to solve the problem of two phase pipe flow using interDyMFoam solver in which two liquid water and air flowing inside the pipe.but both have different velocities so how can i take care of the boundary condition at inlet? at the inlet of the pipe the half portion carries water and another half portion carries air but how can i define B.C.? please help me.

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May 26, 2010, 05:43		#22
sabin.ceuca Member Sabin Ceuca Join Date: Mar 2010 Location: Munich Posts: 42 Rep Power: 16	Hi guys, I am also working on the simulation of 2-phase stratified flow with OpenFOAM. I would recommend to you “Metro”, that you don’t start the simulation with the full “steam” velocity of 10m/s but using a ramp starting from u_steam = u_water. I have experienced a lot of crashes if not preceding so. Greatings Sabin

May 30, 2010, 18:01		#25
metro New Member Join Date: May 2010 Posts: 27 Rep Power: 15	Hey Alberto, I have done the following - 1) decrease the maxdeltaT to 1e-7 (My mistake in the previous thread ) 2) changed the velocities to more realistic figures (1 and 10m/s for liquid and gas) 3) set the internalfield for both the alpha and the velocities (done with funkysetfields and checked in paraView) 4) checked the pressure boundary conditions And it is still not working, Do you have any ideas? Im stuck and realy need some help. Also does anyone have the details on the interPhaseChangeFoam tutorial and the governing equations? Thanks Metro

June 4, 2010, 08:02		#26
sabin.ceuca Member Sabin Ceuca Join Date: Mar 2010 Location: Munich Posts: 42 Rep Power: 16	@Metro can you post your input files? Ok, I am not an advanced user of OF but maybe I can help Greats

June 11, 2010, 01:09		#27
metro New Member Join Date: May 2010 Posts: 27 Rep Power: 15	Thanks for the input. I found that I set the phase interfacial properties incorrectly and as a result it affected the convergence. It seems to be working now. I am currently looking into incorporating a temperature field into the twoPhaseEulerFoam solver. Is there any one who has done this and might be able to assist. Thanks Metro

June 11, 2010, 04:58		#28
sabin.ceuca Member Sabin Ceuca Join Date: Mar 2010 Location: Munich Posts: 42 Rep Power: 16	There are 2 tutorials, take a look at them http://openfoamwiki.net/index.php/Ho...ure_to_icoFoam and http://www.cfd-online.com/Forums/ope...interfoam.html

January 19, 2012, 06:56		#31
sabin.ceuca Member Sabin Ceuca Join Date: Mar 2010 Location: Munich Posts: 42 Rep Power: 16	Hi Jignesh, the solution to your problem is to split your inlet patch in two parts: one for the air inflow the other for the water inlet. If you don't want to remesh your domain, as required in order to split a patch, you can use swak4Foam or groovyBC (just google for them). They help you to define a BC as an expersion of, in your case, (x,y,z). Good luck