Molecular dynamics simulation of nonlinear waves in granular media

Discrete dynamic equations of spheres in granular chains have been developed so as to simulate the evolution of acoustic signals in these media. The model was built based on Hertzian laws as well as the dissipation effect within the system, and the contact dynamics involving both compression and separation between spheres was also modelled. A molecular dynamics simulation method using the Velocity Verlet algorithm was developed to solve the equations. The strongly nonlinear solitary wave impulses are predicted by the numerical calculations and match the experimental results well. The simulation system has been used as a design tool to determine the optimal chain structure in term of the bandwidth and frequencies which are required within the output impulses. The results exhibit great potential in biomedical applications.