scholarly journals The fragmentation of the ocean: spray formation

2012 ◽  
Vol 696 ◽  
pp. 1-4 ◽  
Author(s):  
Yves Couder
Keyword(s):  
Complex System ◽  
Field Measurements ◽  
Single Type ◽  
Sea Spray ◽  
Size Distributions ◽  
Spray Formation ◽  
System A ◽  
Ocean Spray ◽  
Remarkable Result ◽  
Droplet Size Distributions

AbstractBy what process can droplets be extracted out of the sea? This is an old problem, well-documented by precise field measurements of the size distribution of the spray aerosols. Lhuissier & Villermaux (J. Fluid Mech., this issue, vol. 696, 2012, pp. 5–44) study and characterize the bursting of an emerging bubble. They show that this single type of event can, by itself, generate the droplet size distributions in a sea spray. This is a remarkable result showing how, in a complex system, a statistical distribution can be entirely produced by the dynamics of one dominant phenomenon.

Dynamics of Intermittent Sprays

1999 ◽  
Author(s):  
Badih A. Jawad
Keyword(s):  
Droplet Size ◽  
Droplet Size Distribution ◽  
Sampling Technique ◽  
Size Distributions ◽  
Ambient Conditions ◽  
Spray Formation ◽  
Fuel Droplets ◽  
Liquid Immersion ◽  
Particle Sizer ◽  
Droplet Size Distributions

Abstract It is considered that droplet size distribution changes with time and space, since diesel fuel sprays are found to be transient and intermittent due to variations in ambient pressures. Therefore the obscuration signal (extinction of light due to particle field) obtained from a particle sizer for a single injection of fuel over the whole region of spray is necessary to determine the spray characteristics. Previous studies dealing with sprays have observed fuel droplets by use of the sedimentation tower method or liquid immersion sampling technique. However, in these technique droplets are usually sampled after spray formation is complete. The completion time of spray formation appears to vary with ambient conditions, thus making spray measurements under transient conditions during injection difficult. It is the objective of this paper to shine some light on the dynamics of spray motion, leading to a better understanding of the droplet size distributions.

scholarly journals Microphysical Structure of the Marine Boundary Layer under Strong Wind and Sea Spray Formation as Seen from a 2D Explicit Microphysical Model. Part III: Parameterization of Height-Dependent Droplet Size Distribution

2014 ◽  
Vol 71 (6) ◽  
pp. 1914-1934 ◽  
Author(s):  
J. Shpund ◽  
J. A. Zhang ◽  
M. Pinsky ◽  
A. Khain
Keyword(s):  
Wind Speed ◽  
Mixed Layer ◽  
Marine Boundary Layer ◽  
Droplet Size Distribution ◽  
Cloud Base ◽  
Sea Spray ◽  
Observation Data ◽  
Strong Wind ◽  
Size Distributions ◽  
Spray Formation

Abstract This paper completes a series of studies using a 2D hybrid Lagrangian–Eulerian model to investigate the effect of sea spray on the thermodynamics and microphysics of the hurricane mixed layer. The evolution of the mixed layer was simulated by mimicking the motion of an air volume (in a Lagrangian sense) toward a tropical cyclone eyewall along a background airflow. During the radial motion, sea surface temperature, pressure, background wind speed, sea spray production rate, and turbulence intensity were altered according to the available observations. Analysis of the interaction between the hurricane mixed layer and the upper layers in terms of entrainment heat and moisture fluxes gives a new insight into the role of sea spray in the thermodynamics and microphysics of the mixed layer. The evaporation of sea spray leads to an increase in the relative humidity by 10%–15% and to a decrease in temperature by about 1–1.5 K, as compared to cases where sea spray is excluded. Sea spray leads to formation of drizzling clouds with the cloud base at the height of about 250 m. Taking the sea spray effect into account provides a good agreement between the thermodynamics of a simulated mixed layer and the observation data. A parameterization of droplet mass and size distributions as functions of height and wind speed is proposed. The horizontally averaged size distributions are approximated by a sum of lognormal distributions. The moments of size distributions and other integral properties are parameterized as functions of 10-m wind speed by means of simple polynomial expressions.

scholarly journals Modeling the Formation of Urea-Water Sprays from an Air-Assisted Nozzle

2020 ◽  
Vol 10 (16) ◽  
pp. 5723
Author(s):  
Jens Frühhaber ◽  
Christian Lieber ◽  
Dominik Mattes ◽  
Thomas Lauer ◽  
Rainer Koch ◽  
...  
Keyword(s):  
Catalytic Reduction ◽  
Turbulent Dispersion ◽  
Size Distributions ◽  
Two Phase ◽  
Validation Data ◽  
Spray Formation ◽  
Fine Spray ◽  
Computational Fluid Dynamics Cfd ◽  
Breakup Model ◽  
Droplet Size Distributions

Ammonia preparation from urea-water solutions is a key feature to ensure an effective reduction of nitrogen oxides in selective catalytic reduction (SCR) systems. Thereby, air-assisted nozzles provide fine sprays, which enhance ammonia homogenization. In the present study, a methodology was developed to model the spray formation by means of computational fluid dynamics (CFD) for this type of atomizer. Experimental validation data was generated in an optically accessible hot gas test bench using a shadowgraphy setup providing droplet velocities and size distributions at designated positions inside the duct. An adaption of the turbulence model was performed in order to correct the dispersion of the turbulent gas jet. The spray modeling in the near nozzle region is based on an experimentally determined droplet spectrum in combination with the WAVE breakup model. This methodology was applied due to the fact that the emerging two-phase flow will immediately disintegrate into a fine spray downstream the nozzle exit, which is also known from cavitating diesel nozzles. The suitability of this approach was validated against the radial velocity and droplet size distributions at the first measurement position downstream the nozzle. In addition, the simulation results serve as a basis for the investigation of turbulent dispersion phenomena and evaporation inside the spray.

DROPLET SIZE DISTRIBUTIONS OF ADJUVANT-AMENDED SPRAYS FROM AN AIR-ASSISTED FIVE-PORT PWM NOZZLE

2011 ◽  
Vol 21 (3) ◽  
pp. 263-274 ◽  
Author(s):  
Jiabing Gu ◽  
Heping Zhu ◽  
Weimin Ding ◽  
Hong Young Jeon
Keyword(s):  
Droplet Size ◽  
Size Distributions ◽  
Droplet Size Distributions

CONVERSION OF DROPLET SIZE DISTRIBUTIONS FROM PMS OPTICAL ARRAY PROBE TO MALVERN LASER DIFFRACTION

2002 ◽  
Vol 12 (1-3) ◽  
pp. 267-282 ◽  
Author(s):  
Milton E. Teske ◽  
Harold W. Thistle ◽  
Andrew J. Hewitt ◽  
I. W. Kirk
Keyword(s):  
Droplet Size ◽  
Laser Diffraction ◽  
Size Distributions ◽  
Array Probe ◽  
Droplet Size Distributions
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