Void‐fraction measurements and sound‐speed fields in bubble plumes generated by breaking waves

1994 ◽  
Vol 95 (3) ◽  
pp. 1317-1328 ◽  
Author(s):  
Eric Lamarre ◽  
W. K. Melville
Keyword(s):  
Void Fraction ◽  
Sound Speed ◽  
Breaking Waves ◽  
Bubble Plumes

scholarly journals Ocean bubbles under high wind conditions. Part 1: Bubble distribution and development

2021 ◽  
Author(s):  
Helen Czerski ◽  
Ian M. Brooks ◽  
Steve Gunn ◽  
Robin Pascal ◽  
Adrian Matei ◽  
...  
Keyword(s):  
Void Fraction ◽  
Breaking Waves ◽  
Surface Flow ◽  
Stokes Drift ◽  
Gas Transfer ◽  
Langmuir Circulation ◽  
Near Surface ◽  
Wind Speeds ◽  
Void Fractions ◽  
Bubble Plumes

Abstract. The bubbles generated by breaking waves are of considerable scientific interest due to their influence on air-sea gas transfer, aerosol production, and upper ocean optics and acoustics. However, a detailed understanding of the processes creating deeper bubble plumes (extending 2–10 metres below the ocean surface) and their significance for air-sea gas exchange is still lacking. Here, we present bubble measurements from the HiWinGS expedition in the North Atlantic in 2013, collected during several storms with wind speeds of 10–27 m s−1. A suite of instruments was used to measure bubbles from a self-orienting free-floating spar buoy: a specialised bubble camera, acoustical resonators, and an upward-pointing sonar. The focus in this paper is on bubble void fractions and plume structure. The results are consistent with the presence of a heterogeneous shallow bubble layer occupying the top 1–2 m of the ocean which is regularly replenished by breaking waves, and deeper plumes which are only formed from the shallow layer at the convergence zones of Langmuir circulation. These advection events are not directly connected to surface breaking. The void fraction distributions at 2 m depth show a sharp cut-off at a void fraction of 10−4.5 even in the highest winds, implying the existence of mechanisms limiting the void fractions close to the surface. Below wind speeds of 16 m s−1 or RHw = 2 × 106, the probability distribution of void fraction at 2 m depth is very similar in all conditions, but increases significantly above either threshold. Void fractions are significantly different during periods of rising and falling winds, but there is no distinction with wave age. There is a complex near-surface flow structure due to Langmuir circulation, Stokes drift, and wind-induced current shear which influences the spatial distribution of bubbles within the top few metres. We do not see evidence for slow bubble dissolution as bubbles are carried downwards, implying that collapse is the more likely termination process. We conclude that the shallow and deeper bubble layers need to be studied simultaneously to link them to the 3D flow patterns in the top few metres of the ocean. Many open questions remain about the extent to which deep bubble plumes contribute to air-sea gas transfer. A companion paper (Czerski, 2021) addresses the observed bubble size distributions and the processes responsible for them.

Distributions of void fraction under breaking waves in the surf zone

2005 ◽  
Vol 32 (14-15) ◽  
pp. 1829-1840 ◽  
Author(s):  
Ashabul Hoque ◽  
Shin-ichi Aoki
Keyword(s):  
Void Fraction ◽  
Surf Zone ◽  
Breaking Waves

Void fraction measurements in breaking waves

2007 ◽  
Vol 463 (2088) ◽  
pp. 3151-3170 ◽  
Author(s):  
C.E Blenkinsopp ◽  
J.R Chaplin
Keyword(s):  
Void Fraction ◽  
Wave Breaking ◽  
Breaking Waves ◽  
Phase Detection ◽  
Bubble Plume ◽  
Two Phase ◽  
Void Fractions ◽  
Highly Sensitive ◽  
Energy Dissipated ◽  
Degree Of Similarity

This paper describes detailed measurements and analysis of the time-varying distribution of void fractions in three different breaking waves under laboratory conditions. The measurements were made with highly sensitive optical fibre phase detection probes and document the rapid spatial and temporal evolutions of both the bubble plume generated beneath the free surface and the splashes above. Integral properties of the measured void fraction fields reveal a remarkable degree of similarity between characteristics of the two-phase flow in different breaker types as they evolve with time. Depending on the breaker type, the energy expended in entraining air and generating splash accounts for a minimum of between 6.5 and 14% of the total energy dissipated during wave breaking.

scholarly journals Breaking waves and bubble plumes

1993 ◽  
Vol 93 (4) ◽  
pp. 2379-2379
Author(s):  
Peter H. Dahl ◽  
Andrew T. Jessup
Keyword(s):  
Breaking Waves ◽  
Bubble Plumes
Sign in / Sign up

Export Citation Format

Share Document