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Physical modelling of lava flows
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Supervisor:Kerr, Ross Griffiths, Ross
Subject keywords: Volcanoes,Deep Earth/Continent evolution,Ocean dynamics/fluid dynamics,Physics,Laboratory,Experimental,
Degree types: Honours,PhD,
Lava flows contribute to the surface morphology of large areas of the earth, both on continents and on the seafloor, and other planets. They are also sites for the formation of nickel and platinum ore deposits. They may also be used to make inferences about past volcanic activity.
Staff in Geophysical Fluid Dynamics have been studying the dynamics of lava flows through laboratory fluid dynamics analog modelling and theoretical descriptions. This has proven a powerful approach and has shown that the morphology of lava flows is closely controlled by both the eruption rate and surface cooling. Many different types of lava flows can now be seen as members of a sequence of dynamical regimes. The work has involved some of the first ever studies of cooling and solidifying gravity currents.
There are many outstanding questions concerning both melting of underlying rock, solidification of the flow, and mechanisms controlling the cooling of large channel flows. The work may involve interaction with volcanologists from the USA. Contact: Dr Ross Kerr, Professor Ross Griffiths.
Causes of interleaving intrusions between ocean fronts
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Supervisor:Griffiths, Ross Hughes, Graham
Subject keywords: Ocean dynamics/fluid dynamics, Mathematical Geophysics, Physics, Geophysics, Laboratory, Experimental
Degree types: Honours, M.Sc
Where waters of different temperature (T) and salinity (S) lie close to each other in the oceans, there is frequently a region of relatively large lateral T and S gradients (a front). Mixing between the two masses of water is found to involve horizontal finger-like intrusions, often with many interleaved intrusions in a vertical stack. Thermohaline convection is a favoured driving mechanism for these intrusions, but the role of low-frequency internal inertia-gravity waves is unclear. The project will involve laboratory experiments designed to explore the possibility that waves may produce the intrusions and to examine the interactions of internal waves and thermohaline convection.

Energetics of turbulent mixing in real fluids
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Supervisor:Griffiths, Ross Hughes, Graham
Subject keywords: Sea level change/Climate change, Ocean dynamics/fluid dynamics, Mathematical Geophysics, Physics, Geophysics, Laboratory, Experimental
Degree types: Honours, PhD, PhB, Internships
Turbulent mixing in a density stratification is believed to play an essential role in governing the rate of deep overturning circulation in the oceans, and is a common process in many oceanographic and environmental setting. However, the rate of irreversible mixing achieved for a given rate of energy supply to turbulence is poorly understood, as much of the energy is dissipated. In recent work we have developed a better understanding of mixing in a simple fluid. However, real mixing also involves transfer of energy to and from internal chemical potential energy. Through buoyancy this influences the mechanical energy of the flow. There is an opportunity for a PhD student with a physics, mathematics or chemistry background to carry out novel experiments with turbulence in a stratified flow including significant nonlinear mixing effects and to examine the energetics in a more general case.




Dynamics of rotating convection and the ocean overturning circulation
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Supervisor:Griffiths, Ross
Subject keywords: Ocean dynamics/fluid dynamics, Mathematical Geophysics, Physics, Geophysics, Laboratory, Computational, Experimental
Degree types: Honours, M.Sc,
The factors influencing the global deep circulation of oceans are still hotly debated. Even the dominant driving forces are not agreed upon. Yet the circulation and the transport of heat represents an important part of the climate system. At ANU we are examining the fundamentals dynamics of the circulation, using laboratory experiments and computational models to provide tests for theory and to gain new insights into the processes involved. There is an opportunity for a PhD student with a physics or mathematics background to carry out laboratory fluid dynamics experiments and computational work modelling overturning thermal convection in a rotating rectangular basin forced by a horizontal temperature surface temperature gradient. A rich variety of phenomena occur in this system and there is scope to include further complexities.