Hull Slamming

Abstract

This report presents an in-depth review of the current state of knowledge on hull slamming, which is one of several types of slamming problems to be considered in the design and operation of ships. Hull slamming refers to the impact of the hull or a section of the hull as it reenters the water. It can be considered to be part of a larger class of water entry problems that include the water landing of spacecraft and solid rocket boosters, the water landing and ditching of aircraft, ballistic impacts on fuel tanks, and other applications. The problem involves the interaction of a structure with a fluid that has a free surface. Significant simplifications can be achieved by considering a two-dimensional cross section of simple shape (wedge, cone, sphere, and cylinder) and by assuming that the structure is a rigid body. The water is generally modeled as an incompressible, irrotational, inviscid fluid. Two approximate solutions developed by von Karman (1929, “The Impact on Seaplane Floats During Landing,” NACA Technical Note NACA-TN-32) and Wagner (1932, “Uber stoss und Gleitvorgange an der Oberache von Flussigkeiten,” Z. Angew. Math. Mech., 12, pp. 192–215) can be used to predict the motion of the body, the hydrodynamic force, and the pressure distribution on the wetted surface of the body. Near the intersection with the initial water surface, water piles up, a jet is formed, and the solution has a singularity in this region. It was shown that nearly half of the kinetic energy transferred from the solid to the fluid is contained in this jet, the rest being stored in the bulk of the fluid. A number of complicating factors are considered, including oblique or asymmetric impacts, elastic deformations, and more complex geometries. Other marine applications are considered as well as applications in aerospace engineering. Emphasis is placed on basic principles and analytical solutions as an introduction to this topic, but numerical approaches are needed to address practical problems, so extensive references to numerical approaches are also given.

Harmonic oscillations of a thin lamina in a quiescent viscous fluid: A numerical investigation within the framework of the lattice Boltzmann method

“…(12). These two quantities are directly proportional to the added mass and non-linear damping effects, respectively [30].…”

“…Several practical applications have already been successfully investigated such as the design of micro-air vehicles [1][2][3][4][5][6], the development of underwater energy harvesting systems [7][8][9] and the prediction of the hydrodynamic loads acting upon the hull of a ship [10][11][12][13]. From a fundamental viewpoint, the computation of the hydrodynamic load acting upon a vibrating beam (in a quiescent viscous fluid) is a contemporary topic of special interest [14][15][16][17][18].…”

Assessment of PIV-based analysis of water entry problems through synthetic numerical datasets

“…Due to the pile-up phenomenon the effective wetted length r is larger than r n , and we define the pile-up coefficient as ϕ ¼ r=r n (Abrate, 2013). The bulk flow (the water region below the undisturbed free surface) and the pile-up and the spray jets are illustrated in Fig.…”

“…The main challenges in the numerical analysis of water entry problems are associated with the impulsive nature of the impact, which may lead to large numerical oscillations (Hirsch, 2007), and the existence of a free surface, whose motion must be correctly tracked by the numerical solver. A close prediction of the water free surface evolution is particularly relevant for the estimation of the slamming load experienced by the body (Abrate, 2013).…”

Experimental Investigation of the Effects of Flexibility and Surface Properties on Slamming Loads in Water Entry of Cylinders and Spheres

“…Değişen temas alanı neticesinde dövünme katsayısı; olarak ve yine başlangıçta maksimum ancak bu sefer Von Karman'ın değerinin iki katı olarak elde edilir [23].…”