solvers_porousScalarTransport2DFoam

porousScalarTransport2DFoam solver

Description

Solves the transport equation of a passive scalar for free-surface flow in porous media with dispersion coefficient model.

The transport is implicitly solved and based on pre-computed flux phi or velocity U field and water depth hwater

Configuration files

constant/transportProperties :

Example for one specie transport (or multi-species with similar properties):

eps eps [0 0 0 0 0 0 0] 0.25; // porosity (can be volScalarField in constant/)

Dm Dm [0 2 -1 0 0 0 0] 1e-9; // molecular diffusion

porousTransport // specific dictionary for transport
{
  phaseName theta; // to specify the flux field (phitheta here) or velocity field (Utheta)
  Kd Kd [-1 3 0 0 0 0 0] 1e-3;
  rs rs [1 -3 0 0 0 0 0] 1000;
  epsTotal epsTotal [0 0 0 0 0 0 0] 0.30;
  lambda lambda [0 0 -1 0 0 0 0 ] 0;// decay of the C scalar
}

dispersionModel alphaDispersion; // dispersion model

alphaDispersionCoeffs
{
  tau tau [0 0 0 0 0 0 0] 2; // tortuosity
  alphaL alphaL [0 1 0 0 0 0 0] 0.01; // longitudinal dispersivity
  alphaT alphaT [0 1 0 0 0 0 0] 0.002; // transverse dispersivity
}

eventFileTracerSource injectionFile.dat;  // to specify event file for time-dependent source term

Example for multi-species properties can be found at porousScalarTransportFoam page.

system/controlDict :

adjustTimeStep yes;

truncationError 0.001; // Allowed time-scheme truncation error used to manage time-step

CSVoutput       true; // active the CmassBalance.csv output

eventTimeTracking true; // to force the solver to compute solutions at each event time (patch/source/output)

Required fields

• 0/C : The concentration field
• 0/hwater : The pre-computed water depth
• 0/U : Used to compute dispersion coefficient. Can be used to compute 0/phi if not present (Warning: velocity field U in FV formulation is usually reconstructed by interpolation from flux field phi and is not conservative, prefer the use of real phi field from flow field simulation

Optional fields

• 0/phi: The pre-computed flux field where a can be changed in porousTransport dictionary (can be initialized using 0/U)
• Other spatially defined parameters : alphaL , alphaT, eps

Timestep managing

The computation of timestep for next iteration is directly computed using truncation error related to the time scheme defined (Euler, backward, CrankNicolson). The time step formula for backward time-scheme is for example :

deltaT = Foam::pow(3 x truncationError x Cmax[speciesi]/dC3dT3max[speciesi],1./3.)

where dC3dT3maxmaximal is the maximal value of the thid time derivative and Cmax the value of C in this cell.

Return to porousMultiphaseFoam main page