# Numerical problem in species Transport in InterFoam at the interface

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October 11, 2018, 05:15
Numerical problem in species Transport in InterFoam at the interface
#1
Member

Mehdi Aminyavari
Join Date: Feb 2016
Location: Milan
Posts: 35
Rep Power: 8
Hello Forum;
I am trying to introduce a species transport equation in interfoam for the liquid phase (Alpha1 = 1) as bellow:

Code:
```Info << "solve ylEqn.H"<<endl;
surfaceScalarField rho1Phialpha1 = rho1*phi*fvc::interpolate(alpha1);
fvScalarMatrix ylEqn
(
fvm::ddt(alpha1*rho1, yl)
+ fvm::div(rho1Phialpha1, yl, "div(rhoPhiAlpha,yl)")
- fvm::laplacian(alpha1*rho1*Dl, yl)
);```
This equation has been cited 100s of times and thats how people cancell out the gas domain(Alpha1=0) when solving the species balanse for the liquid phase and just solves it where ever Alpha1 is 1 or between 0 and 1.

But the problem is that I get crazy yl values at the interface where 0<Alpha1<1 as you can see in the attached photo! and if I don't bound the yl between 0 and 1 by force, it will go to infinity.
any Idea how to solve this numerical problem? did anybody have done it before?

Attached Images
 Alpha1.jpg (80.0 KB, 31 views) yl.jpg (79.2 KB, 33 views)

 October 11, 2018, 09:20 #2 Member   Mehdi Aminyavari Join Date: Feb 2016 Location: Milan Posts: 35 Rep Power: 8 why my posts have always minimum views among the list??????!!!! is there a trick or something to increase the view and reply??

 October 12, 2018, 02:45 #3 Senior Member   Cyprien Join Date: Feb 2010 Location: Stanford University Posts: 299 Rep Power: 16 Hi, Please, have a look at this paper : https://www.sciencedirect.com/science/article/pii/S0009250918303944 Cheers, Cyprien __________________ www.cypriensoulaine.com/openfoam

 October 12, 2018, 07:01 #4 Member   Mehdi Aminyavari Join Date: Feb 2016 Location: Milan Posts: 35 Rep Power: 8 Dear Cyprien, Thank you so much for your response, I have seen the article, but the point is that you could use the Henry coefficient in this work and make a CST equation because you had a dilute solution which in my case I don't and cant do that. I have to solve the species equation separately for both phases like for phase 1: Code: ```fvScalarMatrix ylEqn ( fvm::ddt(alpha1*rho1, yl) + fvm::div(rho1Phialpha1, yl, "div(rhoPhiAlpha,yl)") - fvm::laplacian(alpha1*rho1*Dl, yl) );``` and the same for Phase 2; and then couple them with a source term. What I can't solve is that as soon as Alpha comes around in the species transfer equations, All goes wrong due to numerical problems introduced at the interface: Any suggestion on that?

 October 12, 2018, 07:03 #5 Senior Member   Cyprien Join Date: Feb 2010 Location: Stanford University Posts: 299 Rep Power: 16 You can if you put H=0. Mehdi3031 likes this. __________________ www.cypriensoulaine.com/openfoam

 October 12, 2018, 07:28 #6 Member   Mehdi Aminyavari Join Date: Feb 2016 Location: Milan Posts: 35 Rep Power: 8 I may explained bad, (Using the notion in your paper): Cj,2 = Hj*Cj,1 so if Hj=0, means Cj,2 = 0 which means in phase two I have no Cj!! In another word phase 2 (gas phase) is pure species i and liquid phase is binary mixture of Species j and i with Cj,1! My problem is Ammonia-water mixture which means in both phases I have both species and it is non-diluted (Cj,2 = 0.95-0.995) and (Cj,1=0.1-0.6) which is as far as I know, not the case to use Henry coefficient. Isn't that right?