Nonlinear characteristics and corrections of near-field underwater explosion shock waves

The shock wave characteristics within the near-field are one of the most challenging aspects of understanding an underwater explosion. The latest numerical and experimental techniques were utilized to investigate the near-field pressure distribution and decay features after a shock disturbance. The governing equations in the numerical simulation were discretized with a fifth-order weighted essentially non-oscillatory scheme in space and a third-order Runge-Kutta scheme in time, and multi-medium interactions were defined and resolved via the modified ghost fluid method. The test system consisted of a synchronized high-speed framing camera and polyvinylidene fluoride (PVDF) sensors. Three identical spherical composition B charges were examined under the same test conditions, and the raw data from the high-speed camera were processed with edge detection and circle fitting techniques. The comparison showed that the high-speed camera image data, the PVDF signals, and the numerical computation results were highly consistent with each other. Higher-order correction terms were added to the pressure peak distribution model and the pressure decay model as nonlinear corrections based on further comprehensive and insightful analysis of the verified results. The corrected models not only fit with the near-field data but had better accuracy under the far-field condition as well.