  The goal of this document is describe the multiphase transfer processes
describing the bubble dynamics of a water electrolyzer. The motivation is to
describe the dilute-dispersed mass transfer within and Alkaline Water
Electrolyzer. Special emphasis is put on the mathematical formulation. The
presentation starts by posing the governing equations and their dimensionless
counterpart. By filtering the equations, the two-fluid model is presented along
with the need to sub-scale and wall models. To the later aim, boundary layer
equations are introduced. By reviewing self-similiarity transformations, the
analysis of Blasius, Ostrach and Sparrow is reviewed for Prandtl's boundary
layer equations; along with that of Leveque.
