Implementing 1D first order PDEs in the weak form

Hi everyone,

I need some help to implement weak form PDEs in comsol.

I'm trying to implement the following system of 1D first order PDEs in the weak form:

with .

In weak form these equations are

So I think that using the "weak form PDE module" I can writte this problem by inserting

-vt*test(phi1) - c1*test(phi1)*Px

-Pt*test(phi2) - c2*test(phi2)*vx

in the "weak form PDE" node and the boundary conditions by using the "dirichlet boundary conditions" node. However, I don't know how to insert the right hand side of the second equation.

For a scalar PDE, tt seems that it can be done by is using the "weak contribution" node at the point of the domain, as I saw in this tutorial. But I don't know how to use the weak contribution node when I have two weak pdes. Anyone know how to help me?

Thanks in advance,

Gustavo