|
[Sponsors] |
simultaneously solve number of diffusion equations |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
August 26, 2014, 09:21 |
simultaneously solve number of diffusion equations
|
#1 |
New Member
Shakil Masum
Join Date: Aug 2014
Posts: 11
Rep Power: 12 |
Hi,
I want to solve these equations using OpenFOAM. The diffusion equations are: dC0/dt = D1 d2/dx2 C0 dC1/dt = D1 d2/dx2 C1 + D2 d2/dx2 C0 (please check the attachment, I have typed them properly in the attachment). I can solve the equations using Laplacian Foam individually. But, I want to solve both equations simultaneously, I mean in every time steps. The problem is the second equation needs the value of C0 (from first equation) in every time step. What changes are required in laplacianFoam.C and also in the '0', 'constant' and 'system' folders? It will be much appreciated. thanks shakil |
|
August 27, 2014, 07:04 |
|
#2 |
New Member
Alex
Join Date: Apr 2011
Location: München
Posts: 13
Rep Power: 15 |
You could try to define your concentrations C1 and C0 as a vector and solve one PDE system instead of two separate PDEs.
That means a volVectorfield instead of a volScalarField in your createFields.H. Best regards, Al |
|
August 27, 2014, 09:59 |
simultaneously solve number of diffusion equations
|
#3 |
New Member
Shakil Masum
Join Date: Aug 2014
Posts: 11
Rep Power: 12 |
Thanks for your reply al_pr.
But I am worried that you cannot consider C0 and C1 as vectors. These are concentrations which are scalars and direction independent. |
|
August 27, 2014, 10:45 |
|
#4 |
Member
Join Date: Nov 2012
Posts: 83
Rep Power: 13 |
you could formulate it is explicit.
Equations. dC0/dt = D1 d2/dx2 C0 dC1/dt = D1 d2/dx2 C1 + D2 d2/dx2 C0 (please check the attachment, I have typed them properly in the attachment). in OpenFOAM: C0Eqn { fvm::ddt(C0) == fvm::laplacian(D1,C0) } C1Eqn { fvm::ddt(C1) == fvm::laplacian(D1,C1) +fvc::laplacian(D2,C0) } |
|
August 27, 2014, 14:07 |
|
#5 |
New Member
Shakil Masum
Join Date: Aug 2014
Posts: 11
Rep Power: 12 |
Dear Henning86,
Thanks a lot. I think this is a brilliant idea. I believe it will also solve the the problem of solving two equations simultaneously in every time step with the updated value of C0 to calculate C1. Am I right to interpret in this way? Thanks again |
|
August 29, 2014, 06:02 |
|
#6 |
Member
Join Date: Nov 2012
Posts: 83
Rep Power: 13 |
yes you are right.
As C1Eqn has an explicit term you are limited by the time step. |
|
Tags |
diffusion, laplacian |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
timeVaryingMappedFixedValue: large data mapping on complex inlet boundaries | vkrastev | OpenFOAM Pre-Processing | 7 | June 2, 2016 16:50 |
compressible flow in turbocharger | riesotto | OpenFOAM | 50 | May 26, 2014 02:47 |
decomposePar pointfield | flying | OpenFOAM Running, Solving & CFD | 28 | December 30, 2013 16:05 |
AMI interDyMFoam for mixer | danny123 | OpenFOAM Running, Solving & CFD | 4 | June 19, 2013 05:49 |
modify fvMatrix / coupled equations / higher order diffusion | Jinming | OpenFOAM Programming & Development | 0 | May 7, 2011 07:20 |