Plunging jet characteristics of plunging breakers

Abstract

: With plunging breaking waves, air bubble entrainment is caused by the top of the wave forming a plunging jet and entraining air when it impacts the water in front of the wave. The potential for air bubble entrainment is related directly to the plunging jet impact characteristics. New experiments were performed in a two-dimensional wave flume.The breaking process was investigated with a high-speed video camera. The results provide new information on the breaking point characteristics, the jet impact conditions and the energy dissipation process. The entrainment of air bubbles is detailed. And the rate of energy dissipation by plunging breakers is estimated.

Void fraction measurements in breaking waves

“…The maximum penetration of the bubble column is greater for the plunging wave cases, reaching depths of approximately 1.8H b , 2H b and 1.4H b for the strongly plunging, plunging and spilling/plunging waves, respectively. These values correspond to 2.4H o , 2.1H o and 1.3H o which are rather greater than the depths of 0.5H o to H o measured by Chanson & Lee (1997) and 0.8H o to 1.5H o by Yüksel et al (1999) who both examined plunging waves using a similar experimental set-up. A probable reason for the greater bubble penetration depth measured in the current experiments is that the optical fibre probe measured over at least 200 waves, while Chanson & Lee (1997) and Yuksel et al (1999) measured between three and five waves for each wave case using a video technique.…”

Bubble Entrainment and Dispersion in Plunging Jet Flows: Freshwatervs.Seawater

“…In the latter, the breaking wave height was about 0.1 m and the writers observed comparatively lesser entrained air than in prototype. Note, however, that the present study was conducted with vertical circular jets, while, at plunging breakers, the plunging jet is quasitwo-dimensional and inclined to about 30Њ with the receiving surface (CHANSON and LEE, 1997). More, it is an unsteady process.…”

“…Some researchers investigated air entrainment at plunging breaker using laboratory experiments of nappes and waterfalls, whereas others applied an analogy between plunging jet flows and plunging breakers: e.g., CHANSON, AOKI, and MARUYAMA, (2002);CHANSON and CUMMINGS, (1994); CHANSON and LEE, (1997);GRIFFIN, (1984); HUBBARD, GRIF- FIN, and PELTZER, (1987); KOGA (1982), Table 1. The analogy DOI:10.2112/03-0112.1 received 16 June 2004accepted in revision 25 June 2004. might be valid during the first seconds of wave breaking.…”

Relationship between high-frequency sediment-level oscillations in the swash zone and inner surf zone wave characteristics under calm wave conditions

“…Houjiangwan is a typical re ective beachface where breaking, plunging type waves mainly occur near the shoreline in the inner surf zone. The plunging breaker produced an overturning of the wave [48,49]. This wave deformation traps air pockets which leads to large quantities of air being entrained [29].…”