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SIMULATION_DATA/readme.txt  (HS 200905)
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This directory contains particle position data from various
dynamical simulations. Each simulation has its own subdirectory,
and the data from selected timesteps is stored into separate 
text-files in this subdirectory.

At the moment (200905) there are two subdirectories,

  IDE
  SIZE

which contain data of the 'standard' simulation models
described in detail in Salo, Karjalainen, French (2004; Icarus 170,70)
(the original simulation directories were called
nr450a130n4_100 and nr450a130n4s_100, respectively, 
which names are retained in the names of individual files).


Each subdirectory has a XXX.posinfo file, summarizing the
simulation. It contains:
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  name of the file (XXX.posinfo)
  date when created
  DIST  = Saturnocentric distance (in units of 1000 km)
  TAU   = geometric optical depth (total area of particles/calculation area)
  SURF  = surface density    (kg/m2)
  RHO   = internal density of particles (kg/m3)
  XL,YL = simulation semiwidths in radial(x),tangential(y) direction (m)
  NPART = number of simulation particles
  EPSMODEL = coefficient of restititution (Bridges, or constant)
  EPSPAR   = paramater of the epsmodel
  SIZEMODEL= describes size distribution 
  S1,S2,Q  = minimum,maximum size and index of powerlaw if applicble
  GRAVLIM  = distance up to which selfgravity is included (m)
  LCR      = Toomre's critical wavelength
  XXX.posdat00    ORB_0	    names of individual files, time in orbital periods
  XXX.posdat01    ORB_1
  ...
  XXX.posdatNN	  ORB_NN	 		
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Each XXX.posdatNN file contains the following variables:

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  name of the file (XXX.posdatNN)
  name of IDL sav-file from which this ascii file was created from
  ORB_nn, XL,  YL,  DY         orbit,  x and y semiwidths, tangential shift
  NPART                        number of particles  
  SS_1, X_1, Y_1, Z_1          particle radius, x, y anz z coordinate (m) 
  ...
  SS_npart, X_npart, Y_npart, Z_npart
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The tangential shift DY indicates the locations of the 'image particles'
beyond the actual simulation region:
each particle at x,y,z has an infine number of replicas at
[i and j go through all integer values]

  x'=   x  + i * (2*XL)
  y'=   y  + j * (2*YL)  + i *DY
  z'=   z

NOTE: if needed, use DY modulo (2*YL) to make sure that -YL < DY < YL


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The SIZE and IDE subdirectories have also

  all.tar.gz

which contains all the individual files in a single gzipped tarfile