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Nonlinear and non-modal stability of structures evolving in shear flows
(University of CambridgeDepartment of Applied Mathematics and Theoretical Physics, 2014-04-08)
This thesis explores a range of stability techniques applied to fluid structures that develop in various constant density flows. In particular, the stability of nonlinear structures which develop in rotating plane Couette ...
Designing a more nonlinearly stable laminar flow via boundary manipulation
(Cambridge University PressJournal of Fluid Mechanics, 2013-12-04)
We show how a fully nonlinear variational method can be used to design a more nonlinearly stable laminar shear flow by quantifying the effect of manipulating the boundary conditions of the flow. Using the example of plane ...
Dynamical instabilities in disc-planet interactions
(University of Cambridge, 2012-01-10)
Protoplanetary discs can be dynamically unstable due to structure induced
by an embedded giant planet. In this thesis, I discuss the stability of such
systems and explore the consequence of instability on planetary ...
Magnetic relaxation, current sheets, and structure formation in an extremely tenuous fluid medium
(IOPScienceThe Astrophysical Journal, 2013-12-03)
The process of relaxation of a unidirectional magnetic field in a highly conducting tenuous fluid medium is considered. Null points of the field play a critical role in this process. During an initial stage of relaxation, ...
Astrophysical tests of modified gravity
(University of CambridgeDepartment of Applied Mathematics and Theoretical Physics, 2014-10-07)
Einstein's theory of general relativity has been the accepted theory of gravity for nearly a century but how well have we really tested it? The laws of gravity have been probed in our solar system to extremely high precision ...
Stratified shear flow: experiments in an inclined duct
(Journal of Fluid Mechanics, 2014-07-22)
We present results of experiments on stratified shear flow in an inclined duct. The duct connects two reservoirs of fluid with different densities, and contains a counterflow with a dense layer flowing beneath a less-dense layer ...
Solving Quasi-Variational Inequalities for Image Restoration with Adaptive Constraint Sets
(SIAMSIAM Journal on Imaging Sciences, 2014-07-11)
We consider a class of quasi-variational inequalities (QVIs) for adaptive image restoration, where the adaptivity is described via solution-dependent constraint sets. In previous work we studied both theoretical and numerical ...
Noise generation by turbulence-propeller interaction in asymmetric flow
(Cambridge University PressJournal of Fluid Mechanics, 2014)
This paper is concerned with a particular source of both broadband and tonal aeroengine noise, termed Unsteady Distortion Noise (UDN). UDN arises from the interaction between turbulent eddies, which occur naturally in the ...
The downward influence of stratospheric sudden warmings
(Journal of the Atmospheric Sciences, 2014-07-14)
The coupling between the stratosphere and the troposphere following two major stratospheric sudden warmings is studied in the Canadian Middle Atmosphere Model using a nudging technique by which the zonal mean evolution of ...