|Version 6 (modified by jmstone, 6 years ago) (diff)|
A large number of problem generators are included in the ./athena/src/prob directory. The purposes of the problem generator are to
- set initial conditions for all variables, in a function that must be called problem and has the following prototype
void problem(DomainS *pDomain)
- enroll any problem-specific boundary conditions, if required. See Boundary Conditions.
- enroll any problem-specific user-defined history outputs, if required. See User-defined Output Variables.
- enroll any problem-specific physics controlled by function pointers, like forces due to a static gravitational potential, or optically-thin cooling.
It will probably be necessary to read the Programmer Guide in order to understand the data structures and Mesh in Athena well enough to write a new problem generator. The existing files in the /src/prob directory can be used as starting templates.
In addition, the file containing the problem() function must also contain a number of other required functions
* problem_write_restart() - writes problem-specific user data to restart files * problem_read_restart() - reads problem-specific user data from restart files * get_usr_expr() - sets pointer to expression for special output data * get_usr_out_fun() - returns a user defined output function pointer * Userwork_in_loop - problem specific work IN main loop * Userwork_after_loop - problem specific work AFTER main loop
In particular, see User-defined Output Variables for a description of how to use the function get_usr_expr() to add new user-defined output variables using one of the existing file formats.
It may also be necessary to include special user-defined functions in the same file that contains the problem generator if new output variables, or new output formats, are used.