AREPO is a parallel moving-mesh code for hydrodynamical cosmological simulations. It is a flexible code that can be applied to a variety of different types of simulations, offering a variety of physics solvers and postprocessing algorithms.
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AREPO is a massively parallel code for gravitational n-body
systems and hydrodynamics, both on Newtonian as well as
cosmological background. It is a flexible code that can be
applied to a variety of different types of simulations, offering
a number of sophisticated simulation algorithms. An description
of the numerical algorithms employed by the code is given in the
original code papers (Springel 2010, MNRAS, 401, 791;
Pakmor et al. 2011, MNRAS, 418, 1392; Pakmor and Springel 2013,
MNRAS, 432, 176; Pakmor et al. 2016, MNRAS,455,1134) and the
release paper of this version (Weinberger et al. 2019).
A user guide can be found under `/documentation`, which also
includes a 'getting started' section, which is recommended for
new users. An html version of the user guide can be created using
sphinx (https://www.sphinx-doc.org) by typing
cd ./documentation/
make html
and displayed by opening `./documentation/build/html/index.html`.
A full version of the user guide is also available on the Arepo
#--------------------------------------- Basic operation mode of code; default: 3d with 6 particle types; type 0: gas >0: only gravitationally interacting
#ENFORCE_JEANS_STABILITY_OF_CELLS # this imposes an adaptive floor for the temperature
#USE_SFR # Star formation model, turning dense gas into collisionless partices
#SFR_KEEP_CELLS # Do not distroy cell out of which a star has formed
#--------------------------------------- Gravity treatment; default: no gravity
#SELFGRAVITY # gravitational intraction between simulation particles/cells
#HIERARCHICAL_GRAVITY # use hierarchical splitting of the time integration of the gravity
#CELL_CENTER_GRAVITY # uses geometric centers to calculate gravity of cells, only possible with HIERARCHICAL_GRAVITY
#NO_GAS_SELFGRAVITY # switch off gas self-gravity in tree
#GRAVITY_NOT_PERIODIC # gravity is not treated periodically
#ALLOW_DIRECT_SUMMATION # Performed direct summation instead of tree-based gravity if number of active particles < DIRECT_SUMMATION_THRESHOLD (= 3000 unless specified differently here)
#DIRECT_SUMMATION_THRESHOLD=1000 # Overrides maximum number of active particles for which direct summation is performed instead of tree based calculation
#EXACT_GRAVITY_FOR_PARTICLE_TYPE=4 #N-squared fashion gravity for a small number of particles of the given type
#EVALPOTENTIAL # computes gravitational potential
#RANDOMIZE_DOMAINCENTER # random displacement to position of domain center; avoids correlated force-errors, important mainly for isolated systems (which otherwise might start to drift in some direction).
#--------------------------------------- TreePM Options; default: no Particle-Mesh
#PMGRID=512 # Enables particle mesh; number of cells used for grid in each dimension
#ASMTH=1.25 # This can be used to override the value assumed for the scale that defines the long-range/short-range force-split in the TreePM algorithm. The default value is 1.25, in mesh-cells.
#RCUT=6.0 # This can be used to override the maximum radius in which the short-range tree-force is evaluated (in case the TreePM algorithm is used). The default value is 4.5, given in mesh-cells.
#PM_ZOOM_OPTIMIZED # Particle-mesh calculation that is optimized for cosmological zoom simulations; disable for cosmological volume simulations.
#PLACEHIGHRESREGION=2 # Places a second, high-resolution PM grid; number encodes high-res particle types from which the extent of this second PM grid is calculated.
#ENLARGEREGION=1.1 # Factor by which high res region is increased with respect to max-min position of high-res particles
#GRIDBOOST=2 # Factor by which PMGRID is increased in non-periodic (or high res) PM calculation (if not set, code uses 2)
#FFT_COLUMN_BASED # Use column-based FFT; slightly slower, but necessary to achieve good load-balancing if number of tasks larger than PMGRID (usually the case for very large runs)
#DOUBLEPRECISION=1 # Mode of double precision: not defined: single; 1: full double precision 2: mixed, 3: mixed, fewer single precisions; unless short of memory, use 1.
#DOUBLEPRECISION_FFTW # FFTW calculation in double precision
#OUTPUT_IN_DOUBLEPRECISION # snapshot files will be written in double precision
#INPUT_IN_DOUBLEPRECISION # initial conditions are in double precision
#OUTPUT_COORDINATES_IN_DOUBLEPRECISION # will always output coordinates in double precision
#NGB_TREE_DOUBLEPRECISION # if this is enabled, double precision is used for the neighbor node extension
#--------------------------------------- On the fly FOF groupfinder
#FOF # enable FoF output
#FOF_PRIMARY_LINK_TYPES=2 # 2^type for the primary dark matter type
#FOF_SECONDARY_LINK_TYPES=1+16+32 # 2^type for the types linked to nearest primaries
#FOF_SECONDARY_LINK_TARGET_TYPES= # should normally be set to a list of all dark matter types (in zoom runs), if not set defaults to FOF_PRIMARY_LINK_TYPES
#FOF_GROUP_MIN_LEN=32 # Minimum number of particles in one group (default is 32)
#FOF_LINKLENGTH=0.16 # Linkinglength for FoF (default=0.2)
#FOF_FUZZ_SORT_BY_NEAREST_GROUP=0 # sort fuzz particles by nearest group and generate offset table in catalog (=1 writes nearest group number to snapshot)
#FOF_STOREIDS # store IDs in group/subfind catalogue, do not order particles in snapshot files by group order
#--------------------------------------- Subfind
#SUBFIND # enables substructure finder
#SAVE_HSML_IN_SNAPSHOT # stores hsml, density, and velocity dispersion values in the snapshot files
#SUBFIND_CALC_MORE # calculates also the velocity dispersion in the local density estimate (this is automatically enabled by several other options, e.g. SAVE_HSML_IN_SNAPSHOT)
#SUBFIND_EXTENDED_PROPERTIES # adds calculation of further quantities related to angular momentum in different components
#--------------------------------------- Things for special behaviour
#RUNNING_SAFETY_FILE # if file './running' exists, do not start the run
#MULTIPLE_RESTARTS # Keep restart files instead of just two copies
#EXTENDED_GHOST_SEARCH # This extends the ghost search to the full 3x3 domain instead of the principal domain
#DOUBLE_STENCIL # this will ensure that the boundary region of the local mesh is deep enough to have a valid double stencil for all local cells
#TETRA_INDEX_IN_FACE # adds an index to each entry of VF[] and DC[] to one of the tetrahedra that share this edge
#NOSTOP_WHEN_BELOW_MINTIMESTEP # Simulation does not terminate when timestep drops below minimum timestep
#TIMESTEP_OUTPUT_LIMIT # Limit timesteps to write snaps on time for output lists with huge range
#ALLOWEXTRAPARAMS # Tolerate extra parameters that are not used
#FIX_SPH_PARTICLES_AT_IDENTICAL_COORDINATES # this can be used to load SPH ICs that contain identical particle coordinates
#RECOMPUTE_POTENTIAL_IN_SNAPSHOT # needed for postprocess option 18 that can be used to calculate potential values for a snapshot
#ACTIVATE_MINIMUM_OPENING_ANGLE # this does not open tree nodes under the relative opening criterion any more if their opening angle has dropped below a minimum angle
#USE_DIRECT_IO_FOR_RESTARTS # Try to use O_DIRECT for low-level read/write operations of restart files to circumvent the linux kernel page caching
#HUGEPAGES # use huge pages for memory allocation, through hugetlbfs library
#DETAILEDTIMINGS # creates individual timings entries for primary/secondary kernels to diagnose work-load balancing
#OUTPUTGRAVINTERACTIONS # output gravitatational interactions (from the tree) of particles
#OUTPUTCOOLRATE # outputs cooling rate, and conduction rate if enabled
#OUTPUT_DIVVEL # output velocity divergence
#OUTPUT_CURLVEL # output velocity curl
#OUTPUT_COOLHEAT # output actual energy loss/gain in cooling/heating routine
#OUTPUT_VORTICITY # output vorticity of gas
#OUTPUT_CSND # output sound speed. This one is only used for tree-based timesteps! Calculate from hydro quantities in postprocessing if required for science applications.
#PROCESS_TIMES_OF_OUTPUTLIST # goes through times of output list prior to starting the simulaiton to ensure that outputs are written as close to the desired time as possible (as opposed to at next possible time if this flag is not active)
#REDUCE_FLUSH # only flush output to log-files in predefined intervals
#OUTPUT_EVERY_STEP # Create snapshot on every (global) synchronization point, independent of parameters choosen or output list.
#OUTPUT_CPU_CSV # output of a cpu.csv file on top of cpu.txt
#HAVE_HDF5 # needed when HDF5 I/O support is desired (recommended)
#HDF5_FILTERS # activate snapshot compression and checksum for HDF5 output
#OUTPUT_XDMF # writes an .xmf file for each snapshot, which can be read by visit (with the hdf5 snapshot)
#--------------------------------------- Testing and Debugging options
#DEBUG # enables core-dumps
#VERBOSE # reports readjustments of buffer sizes
#--------------------------------------- Mesh-relaxing or mesh-adding (this will not carry out a simulation)
#MESHRELAX # this keeps the mass constant and only regularizes the mesh
#ADDBACKGROUNDGRID=16 # Re-grid hydrodynamics quantities on a Oct-tree AMR grid. This does not perform a simulation.
