Oval is a program for discrete element (DEM) modeling of particle assemblies. The program is freely distributed under the open source GNU General Public License, Version 2.
The zip file contains the source code, documentation, and sample assemblies. The source code is Fortran of an f77 flavor. You will need to compile the program using instructions in the documentation. After trying Oval, you may want to contact the author for information about more recent versions of the code: kuhn@up.edu