Ultrafiltration of synthetic fruit juice (mixture of pectin and sucrose) is performed in continuous cross flow mode with an organic ultrafiltration membrane (PPE 30, poly phenylene ethersulfone) of 30 K molecular weight cut off. The permeate fluxes are measured under various operating conditions, namely, transmembrane pressure and cross flow velocity. Significant enhancement of permeate flux is achieved by incorporation of cylindrical promoters placed perpendicular to the flow. Image analyzing video microscopy is used to quantify the deposition profile of pectin on the membrane surface. The consistency of these measurements in relation to enhancement of permeate flux are examined. The coupled fluid flow and mass transfer processes including the effects of the promoters are modeled and solved using FLUENT. The geometry of the system is constructed using GAMBIT and special attentions are given to mesh sizes in the different zones of flow, e.g., finer mesh is used near the membrane surface. The calculated values of permeate flux under various operating conditions agree well with the experimental data. (C) 2008 Elsevier B.V. All rights reserved.