Thomas Albrecht PhD

I study such flows. These animations show the flow generated in a precessing cylindrical container, in two frames of reference: the precessing frame on the left, in which the observer spins with the container and "feels" both rotations, and the rotating frame on the right, in which an observer looks at the spinning container and "feels" only one rotation.

Next to its potential effect on the geodynamo, precession is also important for large-scale atmospheric flows such as cyclones, or for spin-stabilised spacecrafts.

Whenever a solid object—be it a car, a ship, or an aircraft—moves through a fluid, a boundary layer develops right at the object's surface. Although these layers are very thin, they cause significant drag.

Near the object's upstream edge, flow within the boundary layer is usually laminar: smooth, ordered motion which causes comparably little drag. Downstream however, laminar flow becomes unstable and transitions to a turbulent state. Characterised by disordered, chaotic motion, turbulence can increase drag by orders of magnitude.

In my PhD thesis, I investigated how electromagnetic forces affect the transition of laminar flow to turbulence, and how they could be optimised to provide efficient transition delay. This would save fuel, reduce operating costs, and provide greener transport.

The animation shows three cases (left to right). First, the natural flow, which soon becomes turbulent. Second, a flow controlled by a weak, wall-parallel force , which already delays transition. Increasing the forcing amplitude further completely suppresses turbulent flow.