BEGIN:VCALENDAR
VERSION:2.0
PRODID:icalendar-ruby
CALSCALE:GREGORIAN
X-WR-CALNAME:Mathematical Geosciences Seminar - Brad Hindman
X-WR-TIMEZONE:Mountain Time (US & Canada)
BEGIN:VEVENT
DTSTAMP:20261014T072225Z
UID:tag:localist.com\,2008:EventInstance_44376562801895
DTSTART:20230926T170000Z
DTEND:20230926T180000Z
DESCRIPTION:Brad Hindman\, Department of Applied Mathematics\, University o
 f Colorado Boulder\n\nThe Tyranny of Sound: Sound-proofing the fluid equat
 ions\n\nNumerical simulations of convection in low-mass stars\, the Earth
 ’s atmosphere\, giant planets\, and many other astrophysical objects all
  must face the tyranny of sound. Generally\, sound waves propagate quickly
  and have high frequencies\; thus\, the typical timescale associated with 
 acoustics is far shorter than those arising from convection and large-scal
 e circulations. In a numerical simulation\, this short timescale ensures t
 hrough the CFL condition that sound waves control the size of the timestep
  that can be taken while still maintaining numerical stability. The differ
 ence can be dramatic. For example\, at the base of the Sun’s convection 
 zone\, the speed of sound is roughly 200 km/s while the convective flow sp
 eed is on the order of 20 m/s . A numerical simulation that is forced to t
 rack\nsound waves for stability will need to take 10\,000 times as many ti
 me steps to evolve the solution for the same duration as a simulation that
  could ignore the acoustic wave field. This inflation of the necessary com
 putational work is particular onerous since the immense timescale differen
 ce between the deep convection and the sound waves indicates that the two 
 phenomena are essentially decoupled.  I present three different qpproximat
 ions that remove sound waves as a solution of the fluid equations: Boussin
 esq\, anelastic\, and pseudo-incompressible.  I will discuss when each is 
 relevent and when each fails. In particular\, I will explore the differenc
 es between the anelastic and the pseudo-incompressible approximation and d
 emonstrate that the latter is almost always a better approximation to make
 .
GEO:40.006791;-105.262818
LOCATION:Engineering Center\, ECOT 317
SUMMARY:Mathematical Geosciences Seminar - Brad Hindman
URL;VALUE=URI:https://calendar.colorado.edu/event/mathematical_geosciences_
 seminar_-_brad_hindman
CATEGORIES:Colloquium/Seminar
END:VEVENT
END:VCALENDAR