Hello all, need help with the following I am deriving an analytical solution for a problem in petroleum engineering. It concerns fluid flow in porous media. Anyway, the equation is (see attachment) P is pressure, it is a function of space in x-direction, so P(x) d, THETA, and z are just constants What is the general solution ? I think I have to 'transform' it to a version amenable to the 'modified bessel function equation', but I am not sure how to do this. I have the boundary conditions, I can take it from there... Any help would be greatly appreciated !! I am doing this for my masters thesis, this is not just a classic PDE class exercise.