Forces on bubbles and particles in rotating flows
The behavior of bubbles in rotating flows is determined by the effective forces acting on the bubble, like lift and drag forces. At the moment, for both the numerical simulations and the experiments, a rotating geometry is considered. For the experiments, a bubble is injected in a rotating horizontal cylinder, where it reaches an equilibrium position where all forces balance. From the position and the known forces, the lift and drag force can be determined. By doing DNS and assuming some of the forces to be known, others can be determined from the dynamical behavior of a bubble. The project is part of a research project with the goal to improve modeling of turbulent two-phase flows.
Figure 1:Typical bubble trajectory in a rotating cylinder.
Flow around rotating cylinders is of fundamental interest but also of great importance in many industrial applications, for example in flow control. We experimentally investigate the motion of a heavy cylinder in a drum filled with water, and rotating about a horizontal axis. The cylinder either co-rotates or counter-rotates with the rotating drum as shown in Figure 2 below. For the counter-rotation situation, the cylinder freely rotates without contact with the wall of the drum, due to the lift force acting on it.
Figure 2: The inner, freely rotating cylinder either co-rotates (left) or counter-rotates (right) with the drum, depending on the rotation speed of the drum.
The issues we address are:
- The flow mechanisms of both co and counter-rotation situations
- The drag and lift coefficients on the freely counter-rotating cylinder
- Forces due to cylinder rotation and wall vicinity
Researchers: Hanneke Bluemink, Yoshi Tagawa, Chao Sun, Andrea Prosperetti, Leen van Wijngaarden, Detlef Lohse.
Collaborators: Hans Kuipers (Twente), Jaap van der Vegt (Twente), Jacques Magnaudet (Toulouse), Tom Mullin (University of Manchester).
Partners: DSM, Shell, Akzo Nobel, Marin.
Sponsors: STW, FOM.