# Astrophysical Flows

This course presents an in-depth treatment of the dynamics of astrophysical fluids, including both collisional and collisionless fluids, as well as neutral and charged fluids (plasmas). After a first-principles derivation of the various fluid equations (continuity, momentum and energy) linking continuum mechanics to kinetic theory, and a discussion of astrophysical equations of state, we will focus on specific types of flows, including inviscid barotropic flow, turbulent flow, viscous accretion flow, and shocks. We then study various fluid instabilities (convective instability, thermal instability, interface instabilities, gravitational instability) with applications to astrophysics. Next we discuss numerical hydrodynamics, and a few aspects of collisionless dynamics, including dynamical friction and impulsive heating. The course also includes a brief treatment of plasma physics, including plasma orbit theory, magneto-hydrodynamics (MHD), magnetic tension and Alfvén waves, the Vlasov equation, magnetic reconnection and dynamos, and various astrophysical applications of plasma physics. We end with a discussion of the Fluctuation-Dissipation Theorem, and how it connects to the Fokker-Planck equation used to describe a system governed by weak (long-range) encounters.

**Lecture hours: ** Mon-Wed 9.00 – 10.15am, classroom WTS A-60

**Office hours: **Wed 4.00 – 5.00 pm, office 52HH#320

**Syllabus: ** Click here for download

**Lecture Notes: ** PDF document. Click here for download.** NOTE:** lecture notes will be updated throughout the semester. Check back regularly for updates.

**Grading:**

- 35% final exam

- 35% problem sets
- 30% term paper

For more information, use the Yale Canvas System.

**Textbook(s)**

Although no textbook is required (detailed lecture notes are available), students are strongly encouraged to buy the textbook “The Physics of Fluids and Plasmas: An Introduction for Astrophysicists” by Arnab Rai Choudhuri, which covers most of the material covered in class and at the right level. Additional textbooks that are recommended are listed below:

**Problem Sets**

Problem sets (and their solutions) will be made available for download here.

Problem Set 1: due date [Monday Jan 27]

Problem Set 2: due date [Monday Feb 24]

Problem Set 3: due date [Friday Apr 3]

Problem Set 4: due date [not available yet]

Problem Set 5: due date [not available yet]

NOTE: Don’t forget to indicate your name, staple your work, **and always explain your answers to the problem sets**. Points will be subtracted if you fail to explain how you came to the solution, even if it is correct.