Calling the CHIMES Solver

The CHIMES solver replaces the standard cooling routines in the hydrodynamics code. Every hydrodynamic time-step, at the point where you would do the standard cooling, you will need to do the following:

• Loop through all active gas particles/cells.

• Update the gasVariables structure with the particle/cell’s current hydrodynamic quantities (density, temperature etc.). The gasVariables.hydro_timestep should be set to the length of the particle/cell’s hydrodynamic time-step, in seconds. This tells CHIMES how long it needs to integrate the chemistry and cooling for.

• Call the chimes_network(*myGasVars, *myGlobalVars) function, where *myGasVars and *myGlobalVars are pointers to the gasVariables structure for the given particle/cell and the globalVariables structure, respectively. This is the function that will actually integrate the chemical abundances and, if gasVariables.ThermEvolOn == 1, the temperature.

• If cooling was included in the above integration, you will then need to update the particle/cell’s thermodynamic variable(s) in the hydrodynamics code (e.g. the internal energy or the entropy, depending on what is used in the hydro solver), using the final temperature that the particle/cell reached at the end of the time-step, as given in gasVariables.temperature.