|
[Sponsors] |
Problem with Diffusion Equation Implementation |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
February 22, 2019, 12:45 |
Problem with Diffusion Equation Implementation
|
#1 |
Member
Raunak Bardia
Join Date: Jan 2015
Posts: 32
Rep Power: 11 |
Hi all,
I am using OpenFOAM v1706 and trying to make some additions to the interFlow solver. I have initialized a field that is concentrated at the interfacial cells of my two-phase system. It is shown by the attached image (InitialCondition.jpg). I use a simple diffusion equation to diffuse this field on the rest of the grid. The result is shown in the second image (Diffused.jpg). Clearly, the circular symmetry is lost and it has to be due to some error in my implementation of the diffusion equation. But the volume integration of the initial source is conserved to the tolerance level that was specified. Here is my source code used for the diffusion equation spreadSource.H Code:
const dimensionedScalar mdotDiffusionConstant("diff",dimArea,dict_.lookupOrDefault<scalar>("mdotDiffusionConstant",1000)); mdot1 = mdot0; // mdot0 stores the initial condition fvScalarMatrix mdotSpreadEqn ( fvm::laplacian(mdotDiffusionConstant, mdot1) ); mdotSpreadEqn.solve(); createFields.H Code:
// Calculating Source Term at Interfacial Cells volScalarField mdot0 ( IOobject ( "mdot0", runTime.timeName(), mesh, IOobject::NO_READ, IOobject::AUTO_WRITE ), mesh, dimensionedScalar("zero",dimensionSet(1,-3,-1,0,0,0,0),0.0) ); // Distributing Source Term in the domain volScalarField mdot1 ( IOobject ( "mdot1", runTime.timeName(), mesh, IOobject::NO_READ, IOobject::AUTO_WRITE ), mesh, dimensionedScalar("zero",dimensionSet(1,-3,-1,0,0,0,0),0.0), mdotBoundaries ); fvSolution Code:
solvers { "alpha.water.*" { interfaceMethod "isoAdvector"; isoFaceTol 1e-8; surfCellTol 1e-8; snapAlphaTol 1e-8; nAlphaBounds 3; clip true; writeIsoFaces false; writeInterfaceDetails true; phaseChange true; prescribedmdot true; massfluxvalue -100.0; nAlphaCorr 2; nAlphaSubCycles 1; cAlpha 1; MULESCorr yes; nLimiterIter 3; solver smoothSolver; smoother symGaussSeidel; tolerance 1e-8; relTol 0; mdotDiffusionConstant 6.25e-08; } pcorr { solver PCG; preconditioner DIC; tolerance 1e-10; relTol 0; } p_rgh { solver PCG; preconditioner DIC; tolerance 1e-07; relTol 0.05; } p_rghFinal { $p_rgh; tolerance 1e-07; relTol 0; } mdot1 { solver PCG; preconditioner DIC; tolerance 1e-8; relTol 0.1; } mdot1Final { $mdot1; } U { solver PBiCG; preconditioner DILU; tolerance 1e-06; relTol 0; } } PIMPLE { momentumPredictor no; nCorrectors -1; nNonOrthogonalCorrectors -1; nAlphaCorr 1; nAlphaSubCycles 1; cAlpha 1; pRefCell 0; pRefValue 0; } SIMPLE { nNonOrthogonalCorrectors 0; } Thanks. |
|
February 25, 2019, 04:04 |
|
#2 |
Senior Member
Robert
Join Date: May 2015
Location: Bremen, GER
Posts: 292
Rep Power: 12 |
Did you allready take a look at the scalarTransportFoam solver? It solves an advection-diffusion equation. Maybe you can take parts of that eqn. and implement it into your solver.
__________________
If you liked my answer to your question, please consider leaving a "Like" in return |
|
Tags |
diffusion equation, interface advection, openfoam 1706, solver |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Setting the height of the stream in the free channel | kevinmccartin | CFX | 12 | October 13, 2022 22:43 |
turbulent diffusion term in transport equation for additional variables | Raijin Thunderkeg | CFX | 2 | May 17, 2014 23:53 |
Problem in discretising the governing equation. | sahilkala50 | Main CFD Forum | 2 | September 4, 2013 06:45 |
problem on energy and flow equation solving separately | preetam69 | FLUENT | 2 | July 30, 2013 22:08 |
Radial diffusion in scalarTransport problem | jr33 | OpenFOAM | 0 | April 16, 2013 19:22 |