Running

All the solvers are run through the pyro.py script. This takes 3 arguments: the solver name, the problem setup to run with that solver (this is defined in the solver’s problems/ sub-directory), and the inputs file (again, usually from the solver’s problems/ directory).

For example, to run the Sedov problem with the compressible solver we would do:

./pyro.py compressible sedov inputs.sedov

This knows to look for inputs.sedov in compressible/problems/ (alternately, you can specify the full path for the inputs file).

To run the smooth Gaussian advection problem with the advection solver, we would do:

./pyro.py advection smooth inputs.smooth

Any runtime parameter can also be specified on the command line, after the inputs file. For example, to disable runtime visualization for the above run, we could do:

./pyro.py advection smooth inputs.smooth vis.dovis=0

Note

Quite often, the slowest part of the runtime is the visualization, so disabling vis as shown above can dramatically speed up the execution. You can always plot the results after the fact using the plot.py script, as discussed in Analysis routines.

Runtime options

The behavior of the main driver, the solver, and the problem setup can be controlled by runtime parameters specified in the inputs file (or via the command line). Runtime parameters are grouped into sections, with the heading of that section enclosed in [ .. ]. The list of parameters are stored in three places:

• the pyro/_defaults file
• the solver’s _defaults file
• problem’s _defaults file (named _problem-name.defaults in the solver’s problem/ sub-directory).

These three files are parsed at runtime to define the list of valid parameters. The inputs file is read next and used to override the default value of any of these previously defined parameters. Additionally, any parameter can be specified at the end of the commandline, and these will be used to override the defaults. The collection of runtime parameters is stored in a RuntimeParameters object.

The runparams.py module in util/ controls access to the runtime parameters. You can setup the runtime parameters, parse an inputs file, and access the value of a parameter (hydro.cfl in this example) as:

rp = RuntimeParameters()
rp.load_params("inputs.test")
...
cfl = rp.get_param("hydro.cfl")

When pyro is run, the file inputs.auto is output containing the full list of runtime parameters, their value for the simulation, and the comment that was associated with them from the _defaults files. This is a useful way to see what parameters are in play for a given simulation.

All solvers use the following parameters:

[driver]
max_steps	the maximum number of steps in the simulation
tmax	the simulation time to evolve to
init_tstep_factor	the amount by which to shrink the first timestep. This lets the code ramp up to the CFL timestep slowly
max_dt_change	the maximum factor by which the timestep can increase from one step to the next

[io]
basename	the descriptive prefix to use for output files
dt_out	the interval in simulation time between writing output files
n_out	the number of timesteps between writing output files

[vis]
dovis	enable (1) or disable (0) runtime visualization
store_images	if 1, write out PNG files as we do the runtime visualization
n_out	the number of timesteps between writing output files

[mesh]
xmin	the physical coordinate of the lower x face of the domain
xmax	the physical coordinate of the upper x face of the domain
ymin	the physical coordinate of the lower y face of the domain
ymax	the physical coordinate of the upper y face of the domain
xlboundary	the physical description for the type of boundary at the lower x face of the domain
xrboundary	the physical description for the type of boundary at the upper x face of the domain
ylboundary	the physical description for the type of boundary at the lower y face of the domain
yrboundary	the physical description for the type of boundary at the upper y face of the domain
nx	the number zones in the x-direction
ny	the number zones in the y-direction