Abstract

The famous shallow water impacts event at the Chicxulub in Mexico’s Yucatan Peninsula at the Cretaceous–Tertiary boundary 65 million years ago was considered as an important case for tsunami studies. The water entry of a sphere–like asteroid with different impact angle is simulated using a three–dimensional Weak Compressible Smoothed Particle Hydrodynamic model (WC–SPH). The Froude number similarity is used to design a computational model of the scaled model in 1:10000. In order to reduce the computational cost, an Adaptive Particle Refinement (APR) is used. We focus on the evolution of free surface, the formation and propagation of tsunami. The results are compared with the work of Gisler (Gisler, et al., 2004). Though the cavity diameter, height of jet and initial height of tsunami agree well with that of Gisler’ work, the shape of cavity is quite different. This indicates that the fluid compressibility and thermodynamic effects should be considered, at least during the water entry process.

INTRODUCTION

Water entry problem has been one of major concern in marine engineering. However, as a common phenomenon in nature, tsunami induced by an asteroid moving from air into water deserves more concern, because it may cause serious global disaster in the earth. People widely accept that the worldwide mass extinctions at the Cretaceous–Tertiary boundary 65 million years ago was caused by the impact of an asteroid at Chicxulub in Mexico’s Yucatan Peninsula, which was investigated as a shallow water entry problem (Gisler, et al., 2004). The impactor was a bolide of 10km, and its impact was oblique, about 30 degree with the horizon.

Impact energy like that may cause many secondary disasters, such as tsunami, an asteroid the size of 10km fall into water deeper than 1000m, would have sent a 100m tsunami at 4000km distance from the impact location in ocean (Ward and Asphaug, 2002), and the tsunami generated by a 1km asteroid would run 100km and 500km before it was less than 100m and 10m (Crawford, and Mader, 1998).

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