A thin liquid film flows down the outside wall of a cylindrical tube as illustrated below. Species A, present in the gas phase, absorbs into the film at the gas-liquid interface. (A) Use a shell mass balance on species A to derive the governing equations. Your final governing equation should include a velocity profile. Be sure to carefully describe any simplifications you make. TI (B) Identify an appropriate set of boundary conditions to fully characterize the system. Z R R+d