1. Multiphase Reactors, Chemical Engineering and Chemistry, Eindhoven University of Technology; Eindhoven 5600 MB The Netherlands
2. Dept. of Physics and J.M. Burgers Center for Fluid Dynamics; Eindhoven University of Technology; Eindhoven 5600 MB The Netherlands
3. Dept. of Applied Mathematics; University of Twente; Enschede 7500 AE The Netherlands