The head-on collision of a planar shock wave with a rigid porous material has been investigated experimentally in a 75 mm x 75 mm shock tube. The experimental study indicated that unlike the reflection from a flexible porous material (e.g., polyurethane foam) where the transmitted compression waves do not converge to a sharp shock wave, in the case of a rigid porous material (e.g., alumina) the transmitted compression waves do converge to a sharp shock wave, which decays as it propagates along the porous material. In addition to this major difference, many other differences were observed. They are outlined in the following sections.
Based on these observations a suggestion modifying the phenomenology of the reflection/interaction process in the case a porous material with large permeability is proposed. of the differences in the entire interaction/reflection process when the flexible porous material is replaced by a rigid one.
In addition Bear et al. (1992), Sorek et al. (1992), Levy et al. (1993). Levy et al. (1994). Krylov et al. (1994) and Sorek et al. (1994), have initiated recently analytical models for predicting the flow field which is developed inside rigid porous materials under a variety of initial conditions and constrains. The study reported in this paper is also aimed at providing an experimental data base for validating their and hopefully others' analytical models.