Question: A fluid flows down the wall of a wetted wall absorber. A gaseous material is adsorbed into the liquid causing a viscosity variation according to
![1600_mu.png](https://secure.tutorsglobe.com/CMSImages/1600_mu.png)
where µo is the value of viscosity at the film surface. To determine the expression for velocity
![1791_Film.png](https://secure.tutorsglobe.com/CMSImages/1791_Film.png)
a. Draw the control volume (dxxdz) and show the forces acting on it (assume width of film is w). Write the momentum balance and simplify it for this problem, indicating your assumptions for the simplification.
b. Derive the 2nd-order differential equation describing the problem to be solved for velocity as a function of film thickness.
c. What are the boundary conditions for this problem?