Characteristics of Breaking Bow Waves Generated by a 2D+T Wave Maker

Abstract

Ship bow waves simulated experimentally with a 2D+T wave maker were investigated experimentally. Wave profile measurements are presented for a range of equivalent full-scale ship speeds ranging from 16.5 to 27 knots. At the beginning of the wave maker motion, the water surface rises rapidly up the surface of the wave board which represents the hull of the equivalent ship model. The maximum rise height and the rate of rise increase with increasing equivalent ship speed. Later in the wave maker motion, this point of maximum water height moves away from the wave board and forms the primary crest in the wave pattern. This crest moves at a speed that is about 1.8 times the maximum speed of the wave board. At the higher speeds, this wave crest evolves into a strong plunging breaker with a jet that hits the water surface ahead of the breaker, creating a large splash and entraining large amounts of air. The temporal histories of various geometrical characteristics of the breaker are presented.

Boundary between unsteady and overturning ship bow wave regimes

“…The specific example considered here is the bow wave generated by a ship that advances at constant speed U along a straight path in calm water. A ship bow wave is arguably the most visible, complex and important feature of free-surface flow about a ship and accordingly has been extensively studied: numerical and (to a lesser extent) experimental or analytical studies of ship bow waves are reported in Ogilvie (1973), Standing (1974), Chapman (1976), Miyata & Inui (1984), Ç alişal & Chan (1989), Maniar, Newman & Xu (1991), Xu (1991), Tulin & Wu (1996), Dong, Katz & Huang (1997), Roth, Mascenik & Katz (1999), Fontaine, Faltinsen & Cointe (2000), Landrini, Colagrossi & Tulin (2001), , Waniewski, Brennen † Email address for correspondence: francis.noblesse@navy.mil & Raichlen (2002), Karion et al (2003), Muscari & Di Mascio (2004), Landrini (2006), Noblesse et al (2006), Olivieri et al (2007), Noblesse et al (2008 a, b) and Shakeri et al (2008). However, whether a ship in steady motion generates a steady or unsteady bow wave is a basic issue that does not appear to have been examined in the literature, notably in the studies listed above, with the (recent) exception of Noblesse et al (2008b).…”

“…Thus, an experimental validation, based on measurements rather than visual observations, of (1.1) is needed. Although detailed experimental measurements of ship bow waves are reported in several of the previously listed experimental studies, notably Dong et al (1997), Roth et al (1999) and Shakeri et al (2008), these experimental studies do not directly address the issue under consideration. Indeed, no systematic experimental investigation of the boundary between the unsteady and overturning ship bow wave regimes appears to have been reported in the literature.…”