Directory:
    ${PENCIL_HOME}/samples/randum_uu_particles
SVN-Id:
    $Id$
Maintainer:
    Anders Johansen <anders/astro.lu.se>
Added:
    June 2005
Status:
    succeeds # One of [succeeds|failing since <date>|obsolete| ...]
Recommended resolution:
    64x64x64 (nu=2.0e-4)
Comments:
    Tests drag force coupling between gas and particles, including heating, and
    particle collisions.

    For momentum conservation, try:
    IDL> .r momentum

    For energy conservation, try:
    IDL> .r energy

    For analysis of the distribution of particles, try:
    IDL> .r distribution

    The slight non-conservation is probably due to numerical viscosity, since
    the drag force scheme is constructed to conserve momentum.
References:
    Youdin A., & Johansen A.: 2007, ``Protoplanetary disc turbulence driven by
    the streaming instability: Linear evolution and numerical methods'', The
    Astrophysical Journal, vol. 662, p. 613-626, astro-ph/0702625

    Johansen A., & Youdin A.: 2007, ``Protoplanetary disc turbulence driven by
    the streaming instability: Non-linear saturation and particle
    concentration'', The Astrophysical Journal, vol. 662, p. 627-641,
    astro-ph/0702626