Fluid Dynamics and Acoustics
We carry out research in aeroengine and submarine noise; waves and instabilities in boundary layers on aircraft wings; fingering instabilities in thin film flows; combustion instabilities in gas turbines; giant waves and tsunamis; and applications of fluid dynamics to geophysics, especially the atmosphere and oceans, and volcanic lava flows.
Our research in fluid dynamics and acoustics is based on the premise that fundamental analysis of the governing equations, combined with modelling approximations and the use of modern software packages and computational techniques, provide an inexhaustible source of useful results in practical problems. For example, our basic studies of way aircraft engines produce sound rays have been widely used in the aircraft industry; and we have made detailedcontributions to design studies of the acoustic aspects of the next generation of submarines. In turbomachinery research, we are at the centre of an international consortium analysing vibrationand resonance aspects of combustion.
Much of our work relates to the environment, especially as mediated by the atmosphere and oceans. We are experts on all types of waves in the ocean, from ordinary sea waves with which everybody is familiar, to giant `rogue' waves which appear out of nowhere in some seas of the world, and also tsunamis, of such devastating impact, produced by underwater earthquakes. Our research also seeks to understand the mechanisms behind the formation of layers and theprocesses which control the mixing of density or temperature in oceans and lakes.
A crucial aspect of aircraft performance is the response of the boundary layers of air on the wings to incoming disturbances, and the way that these disturbances lead to waves and instability in the fluid flow. We perform high-level mathematical studies, involving asymptotic methods of great sophistication and power, to analyse in detail the properties of these waves,and their effect on aircraft performance.
A fundamental difficulty for human interactions with fluids, in all of the examples above, stems from the disorder introduced by turbulence. We have ongoing research which seeks to obtain order from such chaotic flow by locating so-called unstable ‘exact coherent structures’. These are exact solutions, found computationally, to the governing equations. Due to their instability they are never fully realised in a given evolution, however they offer useful insights into the sustaining processes of the turbulence and can be used to make predictions in an otherwise unpredictable system.
Fluid dynamics is a major aspect of our research under other themes; indeed, it is the ultimate inter-disciplinary subject. For example, see our theme Solid Dynamics and Elasticity for fluid-structure interaction (which is everywhere!), and Biomechanics for the fluid dynamics of thin films, especially in the mucous lining of the lungs.
- Exact coherent structures in fluid turbulence (Dr D. Lucas)
- The ray theory of aircraft noise (Professor C. J. Chapman).
- Global instability in aircraft boundary layers (Professor J. J. Healey).
- The statistical theory of ocean waves (Professor V. I. Shrira, Dr S. Annenkov).
- The asymptotic theory of nonlinear waves in thin Fillms (Dr S. Naire).
- Hani Alahmadi
- Joseph Oloo
- Ed Redfern