$Id: README,v 1.5 2021/02/15 06:25:38 brandenb Exp $

- Linear sound wave (if amplitude is small, typically 1e-2):

   for nx=64, nu_min=5e-3 ==> nu_min/(cs*dx)=0.05

- Nonlinear sound wave (amplitude=1):

   for nx=64, nu_min=1e-1 ==> nu_min/(cs*dx)=1.0
   otherwise mass is not conserved

   for nx=512, nu_min=2e-2 ==> nu_min/(cs*dx)=1.6

Exercises:
==========

1. change the amplitude factors for density and velocity in start.in
   to make the wave traveling forward or backward.
   Monitor the wave, e.g., in idl with IDL> .r pvid

2. increase the amplitude of a traveling wave solution to observe
   the development of a shock. Increase the viscosity to avoid wiggles.
   Check that mass and energy are conserved.

3. change the order of the scheme (itorder=2 or 1), to find out the
   error in energy conservation. You might need to adjust the length
   of the time step by hand (set dt=1e-5 or something).

Additional exercises:
  ~/tex/teach/AdvAstroFluids/ex1