SPARTA example problems

Each of these sub-directories contains a sample problem you can run
with SPARTA.  They should all run quickly in a minute or less on a
desktop machine.  Each problem has an input script (in.*) and produces
a log file (log.*).  Most have dump commands that can be un-commented
to produce a series of image files that animate the simulation.

A few sample log file outputs on different machines and different
numbers of processors are included in the directories to compare your
answers to.  E.g. a log file like log.test.date.machine.P means it ran
on P processors of machine "machine" with the dated version of SPARTA>
Note that these problems should get statistically similar answers when
run on different machines or different numbers of processors, but not
identical answers to those in the included log files.

These are the sample problems in the various sub-directories.  Many
are 2d problems so that they run quickly and can be easily visualized.

ablation = 2d and 3d ablation of implicit surfaces
adapt = static and on-the-fly grid adaptation
adjust_temp = change surf element temps dynamically due to collisions
ambi = amibpolar approxiation for ionized flow around a cylinder
axi = axisymmetric flow around a sphere
bfield = external magnetic field affecting particle motion
chem = chemistry in a 3d box
circle = 2d flow around a circle
collide = collisional motion in a 3d box
custom = custom attributes for particles, grid cells, surface elements
emit = 2d particle emission from surfaces and box face
fft = 2d and 3d FFTs of energy spectrum of a flow
flowfile = particle influx defined by a file of mesh points
free = free molecular motion in a 3d box
python = use of Python in input script
sphere = 3d flow around a sphere
spiky = 2d flow around a spiky circle
step = 2d flow around a staircase of steps
surf = change surfaces between or during runs
surf_collide = variety of surface collision models
surf_react_adsorb = surface reaction adsorb models, both GS and PS variants
tally_computes = tally gas or surface collision and reaction info
thermostat = use of fix temp/rescale as a thermostat
variable_timestep = use of a variable global timestep
vibrate = vibrational energy modes in collisions

Here is an example of how one of the sample problems can be run and
visualized:

cd spiky
cp ../../src/spa_g++ .          # copy DSMC executable to this dir
spa_g++ < in.spiky              # run the problem

Running the simulation produces the files log.sparta and image.*.ppm
(if the dump lines in the input script are uncommented).

View or animate the image files as follows:

display image.0100.ppm         # ImageMagick display program
convert image*ppm movie.gif    # ImageMagick convert -> to animated GIF
firefox ./movie.gif            # run the animated GIF in a browser