I need to solve the problem $\nabla^{2} u(r,\theta,z)=Q(r,\theta,z)$ inside a circular cylinder $(0 < r < a, 0 < \theta < 2\pi, 0 < z < H)$ subject to $u = 0$ on the sides.
I'm supposed to use the eigenfunction method but I'm not very sure of how does it work in cylindrical cordinates. Does anyone know where can I find a good explanation of the method in cylindrical cordinates?
Thank you