| dc.description.abstract | Rayleigh-Taylor instability has been an area of active research in fluid dynamics for
the last twenty years, but relatively little attention has been paid to the dynamics
of problems where Rayleigh-Taylor instability plays a role, but is only one component of a more complex system. Here, Rayleigh-Taylor instability between miscible fluids is examined in situations where it is confined by various means: by geometric
restriction, by penetration into a stable linear stratification, and by impingement
on a stable density interface. Water-based experiments are modelled using a variety
of techniques, ranging from simple hand calculation of energy exchange to full
three-dimensional numerical simulation. Since there are well known difficulties in
modelling unconfined Rayleigh-Taylor instability, the confined test cases have been sequenced to begin with dynamically simple benchmark systems on which existing
modelling approaches perform well, then they progress to more complex systems and
explore the limitations of the various models. Some work on the phenomenology of
turbulent mixing is also presented, including a new experimental technique that allows mixed fluid to be visualised directly, and an analysis of energy transport and mixing efficiency in variable density flows dominated by mixing. | |
