**Course Description**

This course will survey a wide range of basic gas dynamics in an astrophysical context. The conservation equations of hydrodynamics and magnetohydrodynamics will be derived and studied as in any basic physics course in fluid mechanics. Hydrostatics, magneto-statics, virial equilibrium, polytropes, sound and MHD waves, shocks, flux-freezing, kinetic theory, viscosity, and thermal conduction will be included. Following this, the application to astronomical flows will focus on the equations of compressible flow at high Reynolds number. We will discuss steady flows (e.g. stellar winds, accretion, thermal evaporation of interstellar clouds, steady-state radiative shocks), self-similar but non-steady flows (e.g. Sedov blast waves for supernova remnants, cosmological infall and gravitational collapse in an expanding universe, thermal conduction fronts, interstellar-wind-driven bubbles), and non-steady, non-self-similar flows (e.g. ionization fronts and H II regions, cosmological pancakes, the heating and ionization of a cosmological expanding intergalactic medium). We will discuss instabilities such as the Rayleigh-Taylor, Kelvin-Helmholtz, Jeans, and thermal instabilities, and the gravitational growth of cosmological density fluctuations, using linear perturbation analysis. Additional topics may include hydromagnetic dynamos and the generation of cosmical magnetic fields, turbulence, relativistic hydrodynamics, and an introduction to numerical hydrodynamics.

**Prerequisites**

Suitable for all beginning and advanced graduate students in astronomy and physics. Otherwise consent of instructor
is required.

**Requirements**

Homework Problem sets and one end- of-semester student lecture.
A Complete and self-contained set of classnotes will be handed out in place
of a textbook. No exams.

**Homework**

(1) | Lecture note hand-outs will be required reading. |

(2) | Regular homework problem sets will be assigned roughly once per week, due in class one week later (unless otherwise indicated). |

(3) | A student lecture on a topic to be chosen in consultation with and approved by the professor will be scheduled for the final weeks of class, and accompanying lecture notes on this topic will be handed in at this time. |

**Grading**

The course grade will be based on the homework problem set grades, the student lecture, and the accompanying
lecture notes.

23 August 2016

Astronomy Program · The University of Texas at Austin

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