Global existence and decay estimates for the nonlinear wave equations   with space-time dependent dissipative term
  We study the global existence and decay estimates for nonlinear wave equations with the space-time dependent dissipative term in an exterior domain. The linear dissipative effect may vanish in a compact space region. Moreover the nonlinear terms need not divergence form. For getting the higher order energy estimates, we introduce an argument using the rescaling. The method is useful to control derivatives of the dissipative coefficient. 
Tomonari Watanabe
math.AP