Macro-mechanical modeling of blast-wave mitigation in foams. Part III: verification of the models

Abstract

Three different approaches to macro-mechanical modeling of blast-wave mitigation in foam namely: the single-phase effective gas flow model, the two-phase mixture model and the single bubble/shock wave interaction model are critically reviewed. The nature and extent of the approximations inherent in the formulation of the first two models were examined in Part I of this study. In this part, the applicability of the aforementioned approaches is verified based on a comparison of experimental pressure records obtained in shock tube tests with the results of numerical predictions that used the models under consideration. Deficiencies and inconsistencies that are found during this comparison are clarified and possible improvements are suggested. It is emphasized that both the single-phase and the two-phase approaches predict well the refraction of the incident shock at the air/foam interface while they do not uniquely determine the relaxation process and the shape of the transmitted shock wave front. Various flexibilities that are exploited to better describe the inter-phase interactions do not improve the results significantly. The single bubble model is examined with particular attention paid to the manner in which it predicts the shape of the shock wave front. Connections between the flow viscosity and the transient dynamics of the bubble compression that occur at scales of the shock wave front thickness are explored.