Bubbles and particles in a cylindrical rotating flow

To predict the behavior of bubbles and particles moving in fluids, the hydrodynamics forces acting on them need to be known. They are often written in the form of dimensionless coefficients. For some forces, in particular the force at right angles with the velocity, i.e. the lift force, the parameterization of these coefficients is not clear. In this thesis the forces on bubbles and particles in a cylindrical solid body rotating flow are studied, both experimentally and numerically. Experimentally the flow is realized by rotating a horizontal liquid filled cylinder around its axis. A bubble or a buoyant particle will reach a sable equilibrium position in the setup and from this position the drag and lift force can be determined. Some phenomena observed in the flow type under consideration differ from those in many other widely occurring flow types. Examples are a reversal on the lift fore at low Reynolds numbers for a bubble, a freely spinning sphere rotating faster than the surrounding fluid, a lift coefficient which rises with the Reynolds number for a particle, asymmetrical particles and bubbles that drift along the axis of a cylinder. The phenomena and the underlying physics explaining them are discussed.