Comparison of computer codes for propagation of high-frequency energy from blast waves

Abstract

Current environmental regulation requires that the Department of Defense assess the potential impact of noise from military training on endangered wildlife. One concern is the effect of noise from Army weapons on the hearing of bats. High frequencies are generated from nonlinear propagation of finite-amplitude shock waves created by explosions. These frequencies may be harmful to bats because their auditory systems are sensitive to high-frequency information that they use for flight navigation, communication, and hunting. Determining the spatial extent of high-frequency propagation requires an understanding of the short rise times associated with blast waves. A comparison of computer codes is performed for the most sensitive frequency range of bat hearing, 10–100 kHz. Earlier published results by the authors [A. Loubeau and V. W. Sparrow, Proc. NOISE-CON 2004, 193–201 (2004)] are compared to numerical solutions of the generalized Burgers equation with molecular relaxation included. The approaches considered are a time-domain method by Cleveland and a hybrid time–frequency-domain algorithm by Anderson. The results are also compared to recent experimental explosion data obtained by the US Army. [Work supported by US Army Engineer Research and Development Center CERL.]