The demand for instruments that are suitable for the separation of fine particles and biological cells is steadily increasing. Various innovative particles have already implemented in bulk products and many others are close to commercial availability. Tubular bowl centrifuges offer high centrifugal forces at reasonable throughputs. There is a high potential for the optimisation of existing processes and in the design of new tubular centrifuges especially for the separation of nanoscale materials. The separation of fine particulates and biological cells in a semibatch tubular bowl centrifuge at high rotational speeds is described in this work. Furthermore, the influence of the sediment on the process outcome and possibilities to enhance the separation efficiency were investigated. A boundary layer flow was indirectly detected. Structures inside the rotor of the centrifuge cause defined liquid flow patterns, which influence the separation efficiency. A comparison of the separation behaviour with an unimpaired flow and the redirected flow yielded conclusions about the actual flow patterns. (C) 2010 Published by Elsevier Ltd.