MercuryDPM  0.10
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Output Files

MercuryDPM creates three output files, $name.data, $name.fstat and $name.ene.

Here, $name stands for the problem name defined in the code. Data is written at predefined time steps.

Format of $name.data: This file is used for plotting particles. For each time step, the following format is used: 

  First Line: N, time, xmin, ymin, zmin, xmax, ymax, zmax
  N Lines: x, y, z, vx, vy, vz, rad, q1, q2, q3, omex, omey, omez, xi

where N is the number of particles,

  • time denotes the time step,
  • xmin, ymin, zmin, xmax, ymax, zmax denote the domain size,
  • x, y, z are the coordinates,
  • vx, vy, vz are the volocities,
  • rad is the radius,
  • q1, q2, q3 is the angular position,
  • omex, omey, omez is the angular velocity,
  • and xi is an additional variable the user can specify (default 0)

This is the (standard) output required for 3D data; for 2D data, only seven columns of particle information is written: x, y, z, vx, vy, vz, rad, xi

Format of $name.fstat: This file is mainly used for calculating stresses. For each time step, the following format is used: 

  # time, info
  # info
  # info
  Line per contact: time, i, j, x, y, z, delta, deltat, fn, ft, nx, ny, nz, tx, ty, tz

with time step time,

  • particle number i,
  • contact partner j (particles >= 0, walls < 0),
  • the contact point x, y, z,
  • overlap at the contact delta,
  • length of the tangential spring deltat,
  • absolute normal force |f^n|,
  • absolute tangential force |f^t|=|f-f^n|,
  • normal unit vector nx, ny, nz,
  • tangential unit vector tx, ty, tz.

Format of $name.ene: This file is mainly used for interpreting the time evolution. For each time step, the following format is used: 

  time ene_gra ene_kin ene_rot ene_ela X_COM Y_COM Z_COM

with

  • ene_gra $= \sum_i m_i Dot([x,y,z],-[gx,gy,gz])$ the gravitational potential energy (with gravity g=[gx,gy,gz]),
  • ene_kin $= \sum_i m_i v_i^2 / 2$ the translational kinetic energy,
  • ene_rot $= \sum_i I_i \omega_i^2 / 2$ the rotational kinetic energy (with inertia I),
  • ene_ela $= \sum_i (k_i \delta_i^2 + k_i^t (\delta_i^t)^2) / 2$ the potential energy from contact forces,
  • X_COM, Y_COM, Z_COM the center of mass