Rowan Brackston

Research

Feedback Control of Turbulent Bluff Body Wakes

Many road vehicles such as cars and lorries are very aerodynamically ineffecient due to their blunt rear end. However such a shape arises due to practical, operational and aesthetic constraints that cannot easily be adjusted. There is therefore significant motivation for reducing the drag of such vehicles without significant geometric modification. This can be achieved using closed-loop feedback control to modify the properties of the turbulent wake.  Work in this project is focussed on the use of active flaps to implement such a feedback control system, with the aim of regulating flow features such as bistability and vortex shedding for the well documented Ahmed body. Feedback control strategies are developed experimentally at high Reynolds numbers based upon mathematical models of the wake. The control methods are able to modify some of the key flow features and reduce the aerodynamic drag.

Publications

• G. Rigas, A. S. Morgans, R. D. Brackston, and J. F. Morrison. Diffusive dynamics and stochastic models of turbulent axisymmetric wakes . Journal of Fluid Mechanics (Rapid Communication), 778 R2, 2015
• G. Rigas, R. D. Brackston, J. M. Garcia de la Cruz Lopez, J. F. Morrison, and A. Wynn. Drag Reduction Method, Patent pending, 2015

Conferences

• R. D. Brackston, A. Wynn,  J. M. Garcia de la Cruz Lopez, G.Rigas & J. F. Morrison. Feedback Control of Bistability in the Turbulent Wake of an Amed Body, 68th Annual Meeting of the APS Division of Fluid Mechanics, Boston, USA, 2015.
• G. Rigas, A. S. Morgans, R. D. Brackston, and J. F. Morrison, Global and diffusive dynamics of turbulent 3D wakes, 6th symposium on Global Flow Instability and Control, Crete, Greece, 29 September, 2015
• R. D. Brackston, A. Wynn & J. F. Morrison. Observability of the turbulent wake behind an axisymmetric bluff body, 67th Annual Meeting of the APS Division of Fluid Mechanics, San Francisco, USA, 2014.

Education

MEng (Distinction) Aerospace and Aerothermal Engineering, University of Cambridge, 2013
BA cantab (Starred First Class) Aerospace and Aerothermal Engineering, University of Cambridge, 2013