[Yinghao Zhou]

Hello everyone.
I am using the following equation to calculate the electron potential, and k_eff_ele is a constant；
fvScalarMatrix Fai_eleEqn
(
fvm::ddt(tau_potential, Fai_ele)
- fvm::laplacian(k_eff_ele, Fai_ele)
== S_ele
);
When k_eff_ele is a smaller value of 30315, The calculated residual can drop below 1e-7, but when k_eff_ele is a larger value of 2126933, the calculation is difficult to converge. I don't know how to modify the code to make it converge. Can anyone help me?

The fvSchemes is as follows：
ddtSchemes
{
default Euler;

}

gradSchemes
{
default Gauss linear;
}

divSchemes
{
default bounded Gauss upwind;

div(phi_lamda,lamda) Gauss upwind;
div(phi,U) Gauss upwind;
div(phi,K) Gauss upwind;
div(phi,h) Gauss upwind;
div(phi,k) Gauss upwind;
div(phi,epsilon) Gauss upwind;
div(phi,R) Gauss upwind;
div(R) Gauss upwind;
div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
div(phi,Yi_h) Gauss limitedLinear 1;
div(phi,C) Gauss upwind;
}

laplacianSchemes
{
default Gauss linear uncorrected;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default uncorrected;
}

The fvSolution is as follows：
Fai_ele
{
solver smoothSolver;
smoother symGaussSeidel;
tolerance 1e-05;
relTol 0.0001;
}

Fai_eleFinal
{
solver PBiCGStab;
preconditioner diagonal；
tolerance 1e-7;
relTol 0;
}