Explosion cratering in 3D granular media

TL;DR

This study investigates low-energy explosion cratering in 3D granular media, identifying distinct regimes, analyzing crater size dependencies, and establishing scaling relations that connect to high-energy impact cratering physics.

Contribution

It introduces a comprehensive experimental analysis of explosion cratering in 3D granular media, revealing non-monotonic crater size behavior and establishing scaling laws similar to high-energy impact cratering.

Findings

Crater size peaks at an intermediate burial depth.

Crater diameter weakly depends on explosion pressure and duration at small depths.

Crater diameter follows cube root energy scaling, consistent with impact cratering.

Abstract

Sudden release of energy in explosion creates craters in granular media. In comparison with well-studied impact cratering in granular media, our understanding of explosion cratering is still primitive. Here, we study low-energy lab-scale explosion cratering in 3D granular media using controlled pulses of pressurized air. We identify four regimes of explosion cratering at different burial depths, which are associated with distinct explosion dynamics and result in different crater morphologies. We propose a general relation between the dynamics of granular flows and the surface structures of resulting craters. Moreover, we measure the diameter of explosion craters as a function of explosion pressures, durations and burial depths. We find that the size of craters is non-monotonic with increasing burial depths, reaching a maximum at an intermediate burial depth. In addition, the crater diameter shows a weak dependence on explosion pressures and durations at small burial depths. We construct a simple model to explain this finding. Finally, we explore the scaling relations of the size of explosion craters. Despite the huge difference in energy scales, we find that the diameter of explosion craters in our experiments follows the same cube root energy scaling as explosion cratering at high energies. We also discuss the dependence of rescaled crater sizes on the inertial numbers of granular flows. These results shed light onto the rich dynamics of 3D explosion cratering and provide new insights into the general physical principles governing granular cratering processes.