Deterministic and stochastic modeling of the water entry and descent of three-dimensional cylindrical bodies

Abstract

An effective physics-based model has been developed that is capable of reliably predicting the motion of a three-dimensional mine-shaped object impacting the water surface from air and subsequently dropping through the water toward the sea bottom. This deterministic model, MINE6D, accounts for six-degree-of-freedom motions of the body. MINE6D allows for physics-based modeling of hydrodynamic effects due to water impact, viscous drag associated with flow separation and vortex shedding, air entrainment, and realistic flow environments. Unlike existing tools that are limited to plane motions only, MINE6D captures the myriad of complex three-dimensional motions of cylindrical mines observed in field and laboratory experiments. In particular, accounting for the three-dimensional viscous drag and air entrainment cavity produces an accurate prediction of the velocity, trajectory, and orientation of mines freely dropping in the water. The model development and effects on body motion are presented for both viscous drag and air entrainment cavities.

(cont.) Monte Carlo simulation using MINE6D is then used to obtain statistical characterization of mine motions in practical environments. These statistical results are not only the essential input for stochastic bottom impact and burial predictions of mines but also important for the design of mines.