A numerical hydrodynamic simulation of the flow held inside a membrane module has been formulated and implemented. The membrane surface is treated as a porous wall. This simulation is modular in design and can support many optional features such as turbulent effects, pressure-related boundary conditions, and flexible module geometry. The diffusion-convection equation was incorporated in a straightforward manner to model a membrane separation showing the solute concentration field under realistic prevailing hydrodynamic conditions. The numerical results for one-component hydrodynamic simulations match existing but more cumbersome analytical models quite well.