The robustness, reliability and efficiency of modern numerical methods for obtaining solutions to flow problems have given rise to the adoption of Computational Fluid Dynamics (CFD) as a widely used analysis tool for membrane separation systems. In the past decade, many two-dimensional (2D) flow studies employing CFD have been published. Three-dimensional (3D) solutions are also slowly emerging. This paper reviews recent research utilizing 3D CFD models to simulate the flow conditions in narrow spacer-filled channels, such as those encountered in Spiral Wound Membrane (SWM) modules. Many of these studies have focused on optimizing spacer geometric parameters, while others have attempted to gain a better understanding of the mechanisms giving rise to mass transfer enhancement. Applications of 3D CFD to complex spacer geometries and multiple ionic component diffusion are also discussed. (C) 2010 Elsevier B.V. All rights reserved.