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problem with gradient as source term in coupled equations

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Old   August 16, 2010, 13:12
Default problem with gradient as source term in coupled equations
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Cyp
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Hi!

I am trying to implement the following equations in OpenFOAM. There are nspecies resolution of these coupled equations according to the number of species in the system.


http://img148.imageshack.us/img148/6...reenshot1v.png


I have a problem with the implementation of the A-species evaporation rate. There is an error when compiling the code because of the gradient terms in the calculation of Sevap[i].


Code:
// Species transport calculation

for (int i=0; i<= nspecies; i++)
{

    volScalarField& Y_beta_i  = Y_beta[i];
    volScalarField& Y_gamma_i = Y_gamma[i];    
    
    Sevap[i]   = U_gamma_beta[i] & fvc::grad(Y_gamma_i) -U_beta_gamma[i] & fvc::grad(Y_beta_i) - alpha[i]*(H[i]*Y_gamma_i-Y_beta_i);

    mass_evap += Sevap[i];

    solve
    (
        fvm::ddt(eps_beta*rho_beta, Y_beta_i)
      + fvm::div(phi_beta, Y_beta_i)
     ==
        fvm::laplacian(eps_beta*rho_beta*D_beta_beta[i] , Y_beta_i)
      + fvm::laplacian(eps_beta*rho_beta*D_beta_gamma[i], Y_gamma_i)
      + Sevap[i]
    );

    solve
    (
        fvm::ddt(eps_gamma*rho_gamma, Y_gamma_i)
      + fvm::div(phi_gamma, Y_gamma_i)
     ==
        fvm::laplacian(eps_gamma*rho_gamma*D_gamma_gamma[i], Y_gamma_i)
      + fvm::laplacian(eps_gamma*rho_gamma*D_gamma_beta[i] , Y_beta_i)
      - Sevap[i]
    );
}
Here the velocity-like coefficients U_beta_gamma and U_gamma_beta are declared as

Code:
    PtrList<dimensionedVector> U_gamma_beta(nspecies);
    PtrList<dimensionedVector> U_beta_gamma(nspecies);
Do you have any suggestion ??


Moreover, I saw that there is a FvCoupledScalarMatrix class existing. Do you think it is useful in my case or the sequential method can be sufficient enough ?


Regards,
Cyp
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