Propagation of singularities and structure of layers in shells: Hyperbolic case

We consider the boundary layer phenomena which appear in thin shell theory as the relative thickness ε tends to zero. We consider here the hyperbolic case. We focus our attention on the internal layers associated with propagation of singularities along the characteristics. The special structure of the limit problem often implies solutions which exhibit distributional singularities along the characteristics. The corresponding layers for small ε have a very large intensity. Layers along the characteristics have a special structure implying local locking. Numerical experiments using adaptive meshes exhibit the behavior foreseen by using asymptotic methods.