|
[Sponsors] |
multiphaseEulerFoam - Modifying equation used to calculate alpha |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
March 13, 2015, 09:40 |
multiphaseEulerFoam - Modifying equation used to calculate alpha
|
#1 |
Member
Anurag
Join Date: Aug 2014
Location: Germany
Posts: 57
Rep Power: 12 |
Hi everyone,
I would like to make some changes to the way alpha (phase fraction) is calculated in multiphaseEulerFoam. I am still new to it and I have some questions: 1. Calculation of alpha is the first step in the algorithm called by fluid.solve() Now fluid is an object of the type multiphaseSystem. So I check the function Foam::multiphaseSystem::solve() in multiphaseSystem.C However, I still do not seem to understand how exactly is alpha being calculated? Can someone at least point me in the right direction? 2. What does "nAlphaSubCycles" in the fvSolution dictionary do? I read somewhere that this represents the number of additional solutions within a given time step - basically done to calculate "cheaper" alpha while increasing max Co at the same time. But I don't seem to fully appreciate its meaning. Additionally, the fvSolution dictionary in the case mixervessel2D does not define cycleAlpha or nAlphaCorr. Is this not necessary to have a value of nAlphaSubCycles > 1 ? |
|
March 18, 2015, 09:49 |
|
#2 |
Member
Anurag
Join Date: Aug 2014
Location: Germany
Posts: 57
Rep Power: 12 |
Ok. So I have managed to find how alpha is calculated. However, I do not fully understand it yet.
In multiphaseSystem.C, I came across the following equation which is similar to the equation (8) in the relevant paper. Code:
word phirScheme ( "div(phir," + alpha2.name() + ',' + alpha1.name() + ')' ); phiAlphaCorr += fvc::flux ( -fvc::flux(-phir, phase2, phirScheme), phase1, phirScheme ); Thanks in advance. |
|
June 23, 2015, 08:22 |
|
#3 |
Senior Member
Dr. Fabian Schlegel
Join Date: Apr 2009
Location: Dresden, Germany
Posts: 222
Rep Power: 18 |
May be you allready solved this problem, if not here is the explanation. Have a look in gaussConvectionScheme.C. The flux operator evaluates the result of (-fvc::flux(-phir, phase2, phirScheme)) times phase1 for each face (as phase1 is a volScalarField it has to be interpolated to the face).
|
|
July 7, 2015, 07:36 |
|
#4 |
Member
Anurag
Join Date: Aug 2014
Location: Germany
Posts: 57
Rep Power: 12 |
Thank you for the help Fabian. I had stopped looking into this problem altogether and occupied myself a different, although not entirely unrelated, one. I will refer to your comment when I start tinkering with this part of the solver again.
|
|
Tags |
euler-euler, multiphase modelling, phase fraction |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
alphaEqn.H in twoPhaseEulerFoam | cheng1988sjtu | OpenFOAM Bugs | 15 | May 1, 2016 16:12 |
[General] Modifying alpha (opacity) values for a subVolume | paracoder | ParaView | 1 | October 6, 2013 12:47 |
Poisson equation vs continuity equation | DJ | Main CFD Forum | 1 | August 5, 2004 20:01 |
Diffusion Equation | izardy amiruddin | Main CFD Forum | 2 | July 4, 2002 08:14 |
Alpha to be phased out | Heiko Gerhauser | Main CFD Forum | 17 | July 25, 2001 14:40 |