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-   -   multiphaseInterFoam: cycleAlpha (http://www.cfd-online.com/Forums/openfoam/89014-multiphaseinterfoam-cyclealpha.html)

idrama June 1, 2011 09:58

multiphaseInterFoam: cycleAlpha
 
Hello Foamers,

can anybody explain briefly the meaning of cycleAlpha in multiphaseInterFoam.

Cheers in advance

Ohbuchi June 4, 2011 03:10

Hi,
If you cycleAlpha set to 'yes' in fvSolution, reference phase (refPhase) will change in sequential order in the correction loop of "multiphaseMixture.solveAlpha" function.

idrama June 4, 2011 07:02

Okay, I understand so far! But I can't see the purpose; can you explain that, please?

Cheers

Ohbuchi June 4, 2011 16:55

I suppose, cycleAlpha may avoid for accumulating strain to specific phase.

For the reference phase, "alpha = 1 - Sum of alpha other phases".
This constraint must be needed for mass conservation, but for reference phase not very accurate.

alberto June 4, 2011 16:58

Hi,

performing subCycles consists in performing sub-stepping in time. Take a look at:

http://foam.sourceforge.net/docs/cpp..._8H_source.php
http://foam.sourceforge.net/docs/cpp..._8H_source.php

Best,

idrama June 5, 2011 03:41

Strange: Under usage of that option my water phase disappears; if I don't use cycleAlpha then all the phases are there but the min/max values vary from -161 to 31.
Has anybody ever seen anything like that?

In general, are not multiphase phase flow simulation well-engineered?

alberto June 5, 2011 19:05

Quote:

Originally Posted by idrama (Post 310548)
Strange: Under usage of that option my water phase disappears; if I don't use cycleAlpha then all the phases are there but the min/max values vary from -161 to 31.
Has anybody ever seen anything like that?

No I did not see this caused by alpha sub-cycles. More information is required however to answer you properly.

Best,

idrama June 6, 2011 03:14

I wanna simulate a vessel with an thin oil layer at the wall surrounded by air. Initially, there is no water in the tank, rather, the water is being injected via a nozzle. When cycleAlpha is turned on the water jet vanished, and so vice versa. Using the interFoam solver with sub. water and air everything goes fine, even there is no water in the domain at t0.

Ohbuchi June 6, 2011 06:37

2 Attachment(s)
Hi,
I've calculate tutorial case damBreak4phase without cycleAlpha option.
And I attached result of alphaair contour, with or without cycleAlpha.
I think both results are almost same.

Ohbuchi June 6, 2011 06:38

I'm sorry. These contour picture were alphawater, not alphaair.


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