//to implement outflow boundaries correctly we need to loop over all components but the main component as only for the transported ones we implement the outflow boundary. diffusion then is 0.
//now we have to do the tpfa: J_i = J_j which leads to: tij(xi -xj) = -rho Bi^-1 omegai(x*-xi) with x* = (omegai Bi^-1 + omegaj Bj^-1)^-1 (xi omegai Bi^-1 + xj omegaj Bj^-1) with i inside and j outside
//now we have to do the tpfa: J_i = J_j which leads to: tij(xi -xj) = -rho Bi^-1 omegai(x*-xi) with x* = (omegai Bi^-1 + omegaj Bj^-1)^-1 (xi omegai Bi^-1 + xj omegaj Bj^-1) with i inside and j outside