Homogenization of degenerate wave equations with periodic coefficients

In this paper the authors discuss homogenization of hyperbolic equations involving periodic coefficients which are degenerate relative to a certain direction. The general scheme by which effective equations are obtained is as the reiterated homogenization. The first step of the process leads to equations describing the oscillatory behavior in the direction of the propagation. Next, space averaging in the degenerate direction gives the result. The process in the second step produces nonlocal effects.