Theory and simulation of granular materials with hard spheres

摘要

Granular Materials consist of particles that interact during contact, dissipate energy, and possibly rotate due to friction. Such discrete systems are examined with numerical simulations and, sometimes, can also be nicely described by theories like the kinetic theory or hy-drodynamic continuum models. These days, great effort is invested to predict experimental observations quantitatively with simulations and theories. One challenge in computational physics is thus to bridge the gap between the microscopic, "atomistic" simulations, and the macroscopic length scale of continuum models and experimental observation. First, an efficient algorithm for hard sphere molecular dynamics is presented, allowing for many-particle simulations of, e.g., granular systems. In the next step, a "micro-macro" transition is introduced which enables continuum quantities like the stress tensor to be accessed. The approach is used for dilute and dense dissi-pative granular gases, either freely cooling or heated with respect to the translational or rotational degrees of freedom.