Background
The FORTRAN programs below are built from the original hard-particle overlap event-driven simulations written by Mark Hopkins
in the early 1980's, and later modified by Michel Louge. They are
thoroughly commented with all variables defined for all subroutines.
These simulations are designed for granular gases experiencing
binary collisions only. Their execution speed is proportional to the
number of grains, see Hopkins and Louge (1991).
They do not work well under gravity, as particles cannot deform and
overlap slightly for execution speed. Soft-particle algorithms allowing
the granular system to condense include the "contact dynamics" method
of Moreau, Radjai, and collaborators, or the DEM simulations of
Cundall, Walton, Campbell, Silbert, Pöschel and many others.
By changing flags in the input file fexp, our simulations can
simulate microgravity flows in an entire axisymmetric or racetrack
shear cell, or focus on a fully-developed portion of the racetrack with
periodic boundary conditions. Walls can be roughened by hemi-cylinders,
hemispheres, or saw teeth. Synthetic movies can be made through virtual windows placed at position similar to the microgravity experiments from an output of coordinates versus time.
Output diagnostics include longitudinal or transverse profiles of
flow parameters up to the third moments (volume fractions, mean
velocities, relative concentration of two species of spheres, granular
temperature and second moment tensors, collisional and streaming stress
and couple stress tensors, fluxes oftranslational and rotational
fluctuation energies, etc). All output parameters are calculated
following the thorough procedure published by Babic (1997).
To use, download and save the files below, open with MS Word (version 5.1a or later), convert to text files before compilation, and run commands like:
- f77 prepMcGSCv39h.f -o prep & to compile the preparation program
- prep to run prep interactively(if no input file exp is available)
- f77 McGSCv39j.f -o shear & to compile the main FORTRAN program.
- shear < fexp & to run the program with conditions defined in fexp
- then, convert output files to tab-delimited worksheets and graph with any software like Excel
Comments in the source code explain the structure of all inputs and outputs.
Programs
- McGSCv39j.f is the main program.
- McGSComv39j.f states which variables are COMMON to the various subroutines.
- prepMcGSCv39h.f is a program that creates the cell geometry and places grains there.
Utilities
Typical input and output files (zipped)
The zipped document includes all files used to simulate the microgravity experiment reported in "Test I" of M.
Louge, J. Jenkins, H. Xu and B. Arnarson, “Granular segregation in
collisional shearing flows,” in: Mechanics for a New Millennium, A.
Aref and J.W. Phillips, eds., Kluver Academic Publishers (2001), pp.
239-252. These files include:
fexp
pexp
rexpT
rexpT2
rexpsf
rexpsf2
rexptrack2
rexpu
rexpu2
rexpudrift
rexpuu1
rexpuu1sp2
rexpuu2
rexpuu2sp2
rexpuu3
rexpuu3sp2
rexpw1
rexpw1sp2
rexpw2
rexpw2sp2
rexpw3
rexpw3drift
rexpw3sp2
rexpww1
rexpww1sp2
rexpww2
rexpww2sp2
rexpww3
rexpww3sp2
Note: the "exp" file above contains a flow realization that leads to slightly different results than those in the typical output files shown.