GAMMA

GAMMA is a code for modeling relativistic hydrodynamics and non-thermal emission on a moving mesh.

Parts of the code are currently still under development. A full documentation will be made available shortly. For now we provide information on how to compile and run the test cases included with the code.

Requirements

gnu scientific library
OpenMP
MPI

Installation

Clone this repository in a directory of your choice. Move to the directory and build the code.

git clone https://github.com/eliotayache/GAMMA/ dirname
cd dirname
make -B

Usage

running a simulation

Output is stored in ./results/Last. Before you can run calculations you need to create this directory.

mkdir -p results/Last

Use mpirun to launch computation on N_nodes nodes. The code automatically uses all cores available.

mpirun -n N_nodes ./bin/GAMMA -w  # to overwrite files in results/Last
mpirun -n N_nodes ./bin/GAMMA -r  # to resume from the last file in results/Last

choice of module to use

The choice of geometry, time-integration, solver, dimensions are specified in ./Makefile

INITIAL    = Tests/BM1D      # Initial setup: .cpp file in src/Initial (see test examples)
TIMESTEP   = rk3             # euler / rk3
GEOMETRY   = spherical1D     # cartesian / spherical / spherical1D
HYDRO      = rel_sph         # rel_cart / rel_sph
RADIATION  = radiation_sph   # only one option for now
SOLVER     = hllc            # only one option for now
DIMENSIONS = 1d              # 1d / 2d
IO         = text1d          # text1d / text2d

environment variables

A range of self-explanatory environement variables are specified in src/environment.h and should be set before running the code. The non-thermal particle population calculation switches are the following.

#define SHOCK_DETECTION_        ENABLED_
#define DETECT_SHOCK_THRESHOLD_ 0.01
#define LOCAL_SYNCHROTRON_      ENABLED_      # needs SHOCK_DETECTION_ ENABLED_
#define GAMMA_MAX_INIT_         (1.e8)
#define VARIABLE_PSPEC_         DISABLED_     # needs LOCAL_SYNCHROTRON_ and SHOCK_DETECTION_ ENABLED_

initial setup

New initial setups can be created as new .cpp files in src/Initial. These files should follow the same architecture as the example tests in src/Initial/Tests. They specify the initial grid geometry, the initial fluid values, the output times, the AMR criteria and other user-specified (override) functions.

The geometry and fluid state are initialised on a grid Cinit. After initialisation the calculation will be moved to the Ctotgrid that includes ghost cells. The relevant indices to move around the various grids involved in the code are all specified in src/grid.h
In initialValues() the fluid state should be specified in terms of primitive variables S.prim[q] with velocities in units of c.

The following functions have to be declared in this initial file:

void loadParams(s_par *par){}
int Grid::initialGeometry(){return(0);}
int Grid::initialValues(){return(0);}
void Grid::userKinematics(){}
void Cell::userSourceTerms(double dt){}
void Grid::userBoundaries(int it, double t){}
int Grid::checkCellForRegrid(int j, int i){return(skip_);}
void Cell::user_regridVal(double *res){}
void FluidState::cons2prim_user(double *rho, double *p, double *uu){}
void Simu::dataDump(){}
void Simu::runInfo(){}
void Simu::evalEnd(){}

output visualisation

Python plotting functions are available in /bin/Tools/plotting_scripts.py. These functions should be run from this directory.

License

MIT

Publications

GAMMA: a new method for modeling relativistic hydrodynamics and non-thermal emission on a moving mesh (arXiv:2104.09397)

Acknowledgements

This work is funded in part by the European Union’s Horizon 2020 Programme under the AHEAD2020 project (grant agreement n. 871158).

Contact

Feel free to get in touch! eliot.ayache@astro.su.se