[FilipeDias93]

Good afternoon!
I have a question about the usage of the -= command in implementing in volScalarMatrix.
For example, consider the species continuity equation:
ddt(rho)+div(rho*U)+div(J)=w

So, starting by defining the Matrix with the convective terms:
fvScalarMatrix rhoYEqn
(fvm::ddt(rhoY)+fvc::div(rho*U));

Then to add the diffusive term:
rhoYeqn+= fvc::div(J);

And, finally, the source term:
rhoYeqn-= w;

I copied this from another code, and haven't been able to find it elsewhere. The code is also fairly complex, and I can't compare the equations.

My question is this: are the signs on the diffusive and source term correct?

Thank you kindly for your help

[Zeppo]

Seems like everything is fine here. Moreover you can replace
rhoYeqn-= w;
with
rhoYeqn == w;
to state explicitly that your source tern goes to the right hand side.

[FilipeDias93]

Thank you for your help. Is there any page with these kinds of information?

[Zeppo]

Maybe reading the source code can help.