Zonal evolution and prediction model of shock wave pressure field from near-seabed underwater explosions

Abstract

The propagation of shock waves from an underwater detonation near a seabed is governed by the nonlinear interplay among the rigid boundary, evolving gas bubble dynamics, and Mach reflection, producing a highly intricate spatial pressure field challenging to model. In this work, we establish a zonal framework that partitions the pressure field into three physically distinct regions: the reflection amplification region (RAR), the bubble attenuation region (BAR), and the Mach enhancement region (MER). Integrating high-fidelity discontinuous Galerkin simulations, small-scale experiments, and theoretical analysis, we develop predictive models for each region. For the RAR, we propose a dynamic equivalent source method that reconstructs the reflected wave field with an attenuation factor of 1.065. For the BAR, we identify the bubble-shadowing effect and establish an attenuation model with mean absolute percentage error (MAPE) of 6.48%. For the MER, we derive an analytical overpressure model for underwater Mach reflection, complemented by an exponential decay law, yielding a MAPE of 3.33%. The framework is further extended to realistic seabed compositions via material degradation coefficients. On rocky seabeds, Mach reflection occurs only when a dimensionless parameter exceeds 2.321, and the triple-point trajectory is predicted with MAPE of 6.65%. Overall, the framework enables quantitative prediction of the near-seabed pressure field and provides a physically grounded tool for understanding shock-boundary interactions in compressible multiphase flows, with implications for numerical validation and hydrodynamic loading assessment.