1. The problem statement, all variables and given/known data Consider plane waves incident upon an infinitely long cylinder of radius ,a, whose propagation is perpendicular to the axis of the cylinder. 2. Relevant equations This is more of a conceptional question, since the solutions are already developed and just needs to be adapted to the problem. 3. The attempt at a solution I am not sure what kind of boundary condition describes soft scattering. I want to say it is a Neumann boundary condition, since I remember in quantum mechanics doing hard sphere scattering where the boundary condition is a Dirichlet.