Energy Spreading in Strongly Nonlinear Lattices

Dynamics of strongly nonlinear lattices one often describes as ``sonic vacuum,'' as the linear phonons do not exist and the only propagating modes are nonlinear ones. In the presence of a disorder, nonlinear propagating waves do not exist, and the energy spreading, due to chaotic excitation of sites, is characterized by a slow subdiffusion. Using a nonlinear diffusion equation as a phenomenological model, we establish numerically scaling properties of the subdiffusion, for different parameters of nonlinearities.