[Yujuan]

Hi All,

For ordinary diffusion term, like for enthalpy, the diffusion term in the equation could be like fvm::laplacian(turbulence->alphaEff(),he).

Now, I have a equation for x whose diffusion term is like a x div(a1gradx), now I use the expression of a*fvc::laplacian(a1,x) to represent this diffusion term. However, the code just crashed after one step. I'm not sure whether the expression of diffusion term would cause unstability. Could any one give some suggestions? Thanks very much.