CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)
-   OpenFOAM Programming & Development (https://www.cfd-online.com/Forums/openfoam-programming-development/)
-   -   problem with gradient as source term in coupled equations (https://www.cfd-online.com/Forums/openfoam-programming-development/79201-problem-gradient-source-term-coupled-equations.html)

 Cyp August 16, 2010 13:12

problem with gradient as source term in coupled equations

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

 All times are GMT -4. The time now is 08:41.