Shock wave propagation along constant sloped ocean bottoms

Abstract

The nonlinear progressive wave equation (NPE) is a time-domain model used to calculate long-range shock propagation using a wave-following computational domain. Current models are capable of treating smoothly spatially varying medium properties, and fluid-fluid interfaces that align horizontally with a computational grid that can be handled by enforcing appropriate interface conditions. However, sloping interfaces that do not align with a horizontal grid present a computational challenge as application of interface conditions to vertical contacts is non-trivial. In this work, range-dependent environments, characterized by sloping bathymetry, are treated using a rotated coordinate system approach where the irregular interface is aligned with the coordinate axes. The coordinate rotation does not change the governing equation due to the narrow-angle assumption adopted in its derivation, but care is taken with applying initial, interface, and boundary conditions. Additionally, sound pressure level influences on nonlinear steepening for range-independent and range-dependent domains are used to quantify the pressures for which linear acoustic models suffice. A study is also performed to investigate the effects of thin sediment layers on the propagation of blast waves generated by explosives buried beneath mud line.

Application of sand-rubber mixtures to mitigate vibration and ground shock

“…The post processor in LS-DYNA has capability to filter out high frequency noise. Eerden and Berg (2010), Gottlied et al (1981), Kleinschmit (2011) and Maestas et al (2014) reported that blast wave contains mainly low frequency content below 125 Hz.…”