VTK format

In general, VTK is a very versatile format which allows many possible structures. For information on the generic VTK format, please visit the official VTK website. VTK output is known to work with ParaView, a free visualization and data analysis software. Files of this format are supposed to be used as a black box and opened with ParaView, but at the same time they are human-readable text files. This page describes only SMASH-specific VTK format.

SMASH VTK files contain a snapshot of the simulation for a certain output time step. VTK output files are written at the initialization of an event, i.e. the starting time of an event, and at every output time step specified by either Output_Interval or Output_Times. For every output time step a separate VTK file is written.

VTK output is currently implemented for the following output contents:

• Particles:
  • Filename structure: pos_ev<event>_ens<ensemble>_tstep<timestep_counter>.vtk
  • Files contain particle coordinates, momenta, PDG codes, cross-section scaling factors, information if a particle is already formed, ID, number of collisions, baryon number, strangeness, and masses.
• Coulomb:
  • Filename structure:
    • Electric field: Efield_<event>_tstep<timestep_counter>.vtk
    • Magnetic field: Bfield_<event>_tstep<timestep_counter>.vtk
  • Files contain a three vector per lattice cell for the fields. This output requires a Lattice and coulomb potential in the configuration file.
• Thermodynamics:
  • Density on the lattice can be printed out in the VTK format of structured grid.
    • Filename structure: <density_type>_<density_name>_<event_number>_tstep<timestep_counter>.vtk
  • Additionally to density, energy-momentum tensor \(T^{\mu\nu}\), energy-momentum tensor in Landau rest frame \(T^{\mu\nu}_L \) and velocity of Landau rest frame \(v_L\) on the lattice can be printed out in the VTK format of structured grid.
    • Filename structure: <density_type>_<quantity>_<event_number>_tstep<timestep_counter>.vtk

For the possible output configurations see content-specific output options.