Anelastic convection and tidal flows

The discovery of several thousand planets orbiting other stars is the most exciting
development in modern astrophysics. Observations indicate that gravitational tidal
interactions between these planets and their stars have played a crucial role in
modifying the closest systems. It has long been thought that convective turbulence in
the outer parts of evolved stars could efficiently damp large-scale tidal flows, and this
mechanism will probably determine the fate of the Earth when the Sun becomes a red
giant. However, there is a long-standing controversy over its efficiency. The envelopes
of stars and planets contain turbulent convective fluid under the influence of rotation,
with large variations in density. The large density variations (e.g. by 6 orders of
magnitude in the solar envelope) require us to go beyond the well-studied Boussinesq
model for studying the dynamics of convection. This project will employ the anelastic
model (which allows large density variations but omits sound waves) to study the
properties of convection in stars and planets using high-performance numerical
simulations of rotating and turbulent convection. It will then explore the interaction
between a large-scale tidal flow (modelled as a shear flow) and rotating turbulent
anelastic convection, utilising hydrodynamical simulations.