One of the standard tasks in modem chemical industry is solid-liquid separation. While numerous equipments are commercially available to the engineer for separation with cut sizes in the range of several tens of micrometers the number of capable devices is significantly reduced with decreasing cut size. For very small cut sizes in the range of 1-10 mu m none of the established commercially available devices allows sufficient classification with reasonable throughputs and separation sharpness. The present work presents the simulation and optimization of a previously developed classifier that allows sharp separations of suspensions at industrial-scale throughputs with cut sizes in the micrometer range. The optimization was carried out by experimental screening of the influences of main parameters as well as numerical calculation of the flow profile with the CFD program CFX. With the knowledge of the flow profile it is possible to determine and minimize the sources of misclassified particles. The paper explains the results of numerical simulations and the derived optimization as well as its implementation into the design of the prototype and results of initial tests.(c) 2005 Elsevier B.V All rights reserved.