Detail study on the hydrodynamics and concentration polarization phenomenon in the spacer-filled membrane is important to ensure concentration polarization phenomenon can be minimized at minimum energy consumption. The primary goal of this paper mainly focusing on the integration of the permeation properties in commercial CFD codes FLUENT 6 to study the impact of different spacer filaments on unsteady hydrodynamics and concentration polarization in the spacer-filled membrane channel. Based on the velocity contour plot, unsteady vortices emerge, move and dissipate in different spacer-filled membrane channel. Besides, the unsteady hydrodynamic is constrained by the entrance transition effect and only presents at the downstream region of spacer-filled channel. Triangular spacer exhibits the shortest transition length followed by cylindrical and rectangular spacer. Within desirable operating Reynolds number (Re-f < 400), cylindrical spacer can generate lower concentration factor as compared to rectangular spacer. Thus, cylindrical spacer is more appropriate to be used as feed spacer material in spiral wound membrane module. (c) 2006 Elsevier B.V. All rights reserved.