Computational Fluid Dynamics (CFD) and Membranes

The increasing number of CFD membrane studies is clearly related to the recent developments in computer power and to the use of finer grid meshes in the vicinity of the membrane. Two approaches have been particularly considered: the comprehension of the hydrodynamics and of the mass transfer.

The hydrodynamics allows the increase of the shear stress near the wall or the transmembrane pressure thus allowing the enhancement of permeate flux and the membrane processes. CFD allows determining the hydrodynamics, i.e., the pressure and velocity fields, taking into account the geometry of the module and the membranes, the membrane permeability and compactness, as well as the operating entry values such as filtration or backwash pressures, filtration mode, and gravity. For example, it is possible to determine the pressure and velocity fields in (i) a hollow fiber module containing more than 40,000 fibers (small diameter (di = 0.93 mm) and large flow rate (50 m³.h⁻¹) or in (ii) ceramic...