Particles_from_file block

This block contains information about the block used to load particles from file. See EPOCH input deck for more information on the input deck.

The particles_from_file block is similar in function to the fields block, it allows the loading of custom particle data from raw binary data files. An example usage of the block is shown below

begin:particles_from_file 
   species = "electron" 

   # Load mandatory data for 3D simulation
   x_data = "xdata.dat"
   y_data = "ydata.dat"
   z_data = "ydata.dat"
   w_data = "ydata.dat"

   # Load particle ids in 4 byte int format,
   # ignoring first 8 bytes of file 
   #offset = 8
   #id4_data = "iddata.dat"
end:particles_from_file

Specifying a particles_from_file block for a species causes EPOCH to load the per-particle data from the specified files. Data files are assumed to be in order such that the first variable in each file will be attributed to one particle, the second variable in each file to a second electron, and so on. A target species to load to, as well as particle position and weight data (unless has been set) must be supplied. With the exception of particle ID, any optional parameters which are left unspecified will be initialised to zero. If the code has been compiled with or then particle IDs may be loaded from a raw binary file of integers of either size 4 or size 8 regardless of the compile time flag choice. If no particle ID data is supplied, IDs will be generated sequentially from 1. All other data should be in the form of floating point numbers of the same precision as in the core code. A particles_from_file block accepts the following parameters:

• species - Name of the species to which the particles will be loaded. This is a mandatory parameter and the corresponding species block must be defined.

• {x,y,z}_data - File containing particle position data in $m$. This data must be supplied, up to the dimensionality of the simulation.

• w_data - File containing pseudoparticle weight, this is the number of real particles the pseudoparticle represents. This data must be supplied.

• {px,py,pz}_data - File containing particle momentum data in $kg,ms^{-1}$. The default value is zero.

• id{4,8}_data - File containing particle IDs in either 4 or 8 byte unsigned integer representation.

• offset - File offset. Number of bytes at the head of the file to be ignored, may be specified multiple times. see for more details of behaviour.