A submerged submarine is towed horizontally at a steady speed U in deep, still water. Far behind

Fantastic news! We've Found the answer you've been seeking!

Question:

A submerged submarine is towed horizontally at a steady speed U in deep, still water. Far behind at a fixed distance from the submarine an axially-symmetrical wake is formed in which the water velocity may be assumed to vary linearly from U down to zero on the axis. Find the drag on the submarine and the power required to tow it.