Astronomy/Physics 202
Astrophysical Fluid Dynamics
(Fall 2024)
Problem Set 9 (due 6pm Thursday December 12)
Reading:
Ch 2, 4, 8 of Balbus MHD; MRI review paper
Excellent intro article on turbulence: The Turbulence Problem by Robert Ecke (2005).
Turbulence: golf ball
dimples. What happens when only half of the ball has dimples?
Flying snake and lizard.
TEDx talk.
Laminar flow
Images of billow clouds, above SF, Chung-Pei's shot, Starry Night
AREPO code: paper
K-H instability
single mode,
random noise initial seeds
R-T instability: injecting dye in water movie
R-T instability single mode
Crab Nebula
October 28 Monday
- Olivia Aspegren: Fluid dynamics of tennis. Talk slides.
- Ethan Levin: Diffusion flames. Talk slides.
October 30 Wednesday
- Savannah Cary: Supernova ejecta. Talk slides.
November 4 Monday
- Fatima Yousuf: Earth climate modeling. Talk slides.
- Peter Ma: Physics-inform neural networks for fluid dynamics. Talk slides.
November 6 Wednesday
- Katie Sharpe: Superfluidity. Talk slides.
- Cooper Jacobus: Simulating the cosmic web. Talk slides.
November 13 Wednesday
- Dylan Motley: Shock wave/boundary layer interactions in hypersonic vehicles. Talk slides.
November 18 Monday
- Hao-Tse Huang: Stellar oscillations and chaotic tides. Talk slides.
- Keaton Ferguson: Saturn's hexagonal storm. Talk slides.
November 20 Wednesday
- Evan Kaplan: Helium flash and combustion in stellar envelopes. Talk slides.
- Saahit Mogan: Fluid dynamics of traffic flows. Talk slides.
November 25 Monday
- Stephon Qian: Stellar rotations and the Tayler-Spruit instability. Talk slides.
- Tamar Ervin: Astrophysical turbulences. Talk slides.
Email me your preferred topic by 5pm Wednesday October 2.
See samples below. You are encouraged to select and define
your own topic.
Format: Each talk is 15 minutes. The audience is your
classmates, and pedagogy is important.
Each topic is likely broad and
has consumed many professional astro/physicists' lives. Focus on
big questions such as:
Why is it important?
How is it done?
What have we learned?
What are the current limitations in understanding this problem/phenomenon?
What to expect next?
Be sure to draw connection to the equations
and theories derived in class, but don't spend time on derivations.
Instead, emphasize applications, phenomenology, and how theories/models can and can't explain and predict observations.
Sample topics: Earth climate, ocean, tsunami,
tornadoes, planet atmospheres, solar wind, helioseismology,
astrophysical accretion disks, examples of fluid instabilities,
physics of baseball, numerical simulations of galaxy formation and
many more.
Problem Set 8 (due 6pm Friday November 22)
Problem Set 7 (due 6pm Friday November 8)
Reading:
Ch 13.7 of Thorne and Blandford; Ch 7 of Balbus "Hydrodynamics"
Problem Set 6 (due 6pm Friday October 25)
Problem Set 5 (due 6pm Friday October 18): An outline (1-2 pages) of your present
aion. Sketch the scope of the talk. Provide references (i.e. review/journal papers; web links
) that you are using to learn the topic. The more detail you provide, the more feedback we can give you.
Problem Set 4 (due 6pm Friday October 11)
Reading: Ch 17 of Thorne and Blandford
Problem Set 3 (due 6pm Friday October 4)
Reading: Ch 16 of Thorne and Blandford
Problem Set 2 (due 6pm Friday September 27)
Problem Set 1 (due 6pm Friday September 20)
Reading:
Ch 13.1-13.6 of Thorne and Blandford
Instructor:
Chung-Pei Ma
Office: Campbell Hall 319
Email: cpma(at)berkeley.edu
Office hours: 11:30-noon MW (right after class in 501B)
Reader:
Jacob Pilawa
Email: jacobpilawa(at)berkeley.edu
Help sessions: 5pm Wednesdays (zoom link)
Lectures: MW 10:10-11:30am in Campbell 501B
Grading: 70% problem sets; 30% in-class presentation
Main References:
- Thorne and Blandford: Modern Classical Physics (Princeton University Press 2017). A pre-published version (January 2013) is available here. Ch 13: Foundations of Fluid Dynamics
- Balbus text: Hydrodynamics, Magnetohydrodynamics
Supplementary References:
- Clarke and Carswell: Principles of Astrophysical Fluid Dynamics (Cambridge University Press 2007)
- Pringle and King: Astrophysical Flows (Cambridge 2007)
- Shu: Gas Dynamics (University Science Books 1992)
- Tritton: Physical Fluid Dynamics (Oxford Press 1988)
- Acheson: Elementary Fluid Dynamics (Oxford Press 1990)
- Landau and Lifshitz: Fluid Mechanics (1987)
- Binney and Tremaine: Galactic Dynamics (Princeton Press 2008)
Course Content:
- 1. Basic Stuff about Fluids
- 1.1 Fluid approximation; fluid element
- 1.2 Derivatives; Eulerian vs Lagrangian
- 1.3 Mass conservation: continuity equation
- 1.4 Momentum conservation: Euler equation; pressure; stress tensor
- 1.5 Energy conservation; equation of state
- 1.6 Examples of simple solutions: hydrostatic equilibrium; polytropic star; Lane-Emden equation
- 1.7 Bernoulli's principle
- 2. Waves and Flows
- 2.1 Sound waves
- 2.2 Gravity waves, surface water waves, capillary waves
- 2.3 Shock waves: jump conditions
- 2.4 Blast waves; Sedov-Taylor similarity solutions; supernova remnants
- 2.5 Supersonic flows: de Laval nozzle, Bondi accretion
- 3. Fluid Instabilities
- 3.1 Gravitational instability: Jeans length, static vs expanding medium
- 3.2 Gravitational instability in rotating disks: uniform vs differential rotation, epicycle frequency
- 3.3 Rayleigh-Taylor instability
- 3.4 Kelvin-Helmholtz instability
- 3.5 Thermal instability: conduction, multi-phase medium
- 4. Sticky stuff
- 4.1 Viscous stress tensor and force: heuristic and mathematical derivations
- 4.2 Navier-Stokes equation; Reynolds number
- 4.3 Applications: Poiseuille flow, Stokes flow
- 4.4 Accretion disk: molecular vs turbulent viscosity
- 5. Kinetic Theory
- 5.1 Phase space; distribution function; Boltzmann equation
- 5.2 Comparison to fluids: infinite hierarchy, closure relations
- 5.3 Collisionless vs collisional matter: physics of the cosmic microwave background
- 5.4 Stochastic processes; diffusion; Fokker-Planck equation
- 6. MagnetoHydroDynamics
- 6.1 Motivation; Maxwell's equations
- 6.2 Ohm's law; induction equation; magnetic Reynolds number
- 6.3 Ideal MHD; magnetohydrodynamic waves; Alfven speed
- 6.4 Magnetorotational instabilities
- 7. Turbulence
- 7.1 Laminar vs turbulent flows
- 7.2 Energy cascade; Kolmogorov spectrum
- 7.3 Applications: smoke, golf ball, atmospheric seeing
- 8. Applications (student presentations)
- Examples: climate, ocean, tsunami, tornadoes, planet atmospheres, solar wind, helioseismology, astrophysical accretion disks, examples of fluid instabilities, physics of baseball, hydrodynamical simulations of galaxy formation, drip paint, flying snakes, and many more.
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