A very large number of astrophysical systems can be modelled as fluids that move under the action of two external forces (gravity and electromagnetism) as well as the forces exerted internally on the fluid by its adjacent parts as they jostle one another in their motion. An added complication is that the fluid material is a thermodynamic system: it is able to absorb, store, and expel energy as it moves. A fluid is therefore a complex system whose motion is governed by the laws of gravity, electrodynamics and thermodynamics.
The fluid flows observed here on earth occur everywhere in the universe, but on a grander scale and under far more extreme conditions. In this course, we study the elements of fluid dynamics and learn how to describe simple flows. For simplicity, we ignore electromagnetic forces. The study of their effects on flow is the subject of magnetohydrodynamics, which will be studied in the Masters course. This course concentrates of flows that are driven by gravity, pressure and thermodynamics. The theory developed in the lectures is illustrated by examples both of terrestrial and astrophysical flows.
Fluid dynamical processes are the driving force behind most fundamental processes in the universe, i.e. spiral density waves in galaxies, triggering bursts of star formation in the spiral arms as it passes through a region, solar and stellar flares, stellar evolution, instabilities in stars giving rise to stellar pulsation, accretion processes in binary systems, as well as the super-relativistic jets ejected by black holes in the heart of galaxies, and many others. Fluid dynamics is thus central to a good understanding of astrophysics and astrophysical processes.
The aim of this course is to provide aspiring astrophysicists with a broad introduction to the fundamental fluid processes that you can expect to feature in a wide range of astrophysical environments.