Experimental cloud droplet collection efficiencies

Abbott, Charles E.

doi:10.1029/jc079i021p03098

Cited by 20 publications

(8 citation statements)

References 12 publications

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“…Except for drops of nearly equal size, these results were used in constructing the curves. Woods and Mason [1965b] noted, as did Abbott [1974], that this technique does not record effects occurring over widely separated vertical distances. Abbott observed high rates of collision between droplets of nearly equal radii of 25-50 • resulting in collection efficiencies exceeding 1.0, which had also been reported by Telford et al [1955] for 77-• drops.…”

Section: Concentrated Upon Interactions Between Relatively Small Dropmentioning

confidence: 99%

A survey of Waterdrop Interaction Experiments

Abbott¹

1977

Reviews of Geophysics

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The growth of waterdrops by inertial capture and coalescence induced by the size‐dependent terminal velocities in the earth's gravitational field is an important process in the formation of rain. The extensive experimental data on this fundamental process are reviewed and organized into a coherent summary of the collection efficiencies applicable to natural clouds, in the following circumstances: negligible effects of electric charges and fields, normal laboratory temperatures and pressures, and relative humidities between 50 and 100%. The judgments required to reduce the experimental data to the brief summary form are documented.

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Section: Concentrated Upon Interactions Between Relatively Small Dropmentioning

confidence: 99%

A survey of Waterdrop Interaction Experiments

Abbott¹

1977

Reviews of Geophysics

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“…The wake effects behind the collector drop can produce values of collision efficiency greater than unity (Wallace and Hobbs, 1977). The collection efficiency of nearly equal size drops has been found to be large (Abbot, 1974) even for drops as small as 25 pm radius.…”

Section: Introductionmentioning

confidence: 97%

An experimental investigation of the influence of electric field on the collision-coalescence of water drops

Paul

Selvam

Murty

1979

Tellus A: Dynamic Meteorology and Oceanography

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Laboratory experiments were conducted on the collision-coalescence of pairs of water drops of equal size, in two oil media (kerosene and mustard), with and without external vertical electric field (F). The radii of the water drops used were in the range 1.6 to 1.7 mm and the external electric field varied from 0 to 375 V cm-'. Collision frequencies were determined for various combinations of mean lateral (X) and mean vertical (Z) separations of the drop pairs as fixed combinations of X and Z could not be reproduced in any given set of experiments due to the limitations of the mechanical set up of the apparatus.The collision frequency (E) for any given initial values of X and Z decreased with F up to a certain value of F and thereafter increased. The variations observed in the collision frequency under different external electric fields have been explained quantitatively based on the electrostatic theory of polarization charges. The vertical distance travelled by the pair of drops prior to a collision was less with the external electric field. For collision to occur at a fixed depth (d), the values of Z increased with F when X was zero. For the same initial conditions, collision took place earlier in kerosene than in mustard oil medium. The collision efficiency (Ex), computed from the measured values of the radius of the collisioncross-sectional area, was less in the presence of external electric field. The drops did not coalesce without the external electric field. The coalescence frequency (E,) increased with F. The field values for 100% coalescence were lower in mustard oil as compared to those in kerosene. The path length between collision and coalescence events sharply decreased with increase of F. The collection efficiency was zero without external electric field and it increased with F. In the case where the collected drop was slightly smaller than the collector drop the collection efficiency was more compared to that when the drops were of equal size.

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“…Although extensive experiments have been performed on the Brownian coagulation of aerosols, 30,31 the experimental knowledge of aerosol coalescence due to turbulence is lacking. Such experiments require a precise characterization of the turbulent flow field; they also need accurate measurements of the change in the properties of aerosols with sufficiently high concentrations so that the coalescence rate is significant.…”

Section: About Experimentsmentioning

confidence: 99%

An industry-scale modeling for the turbulence agglomeration of fine particles

Shen

Wang

2015

Advances in Mechanical Engineering

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Turbulence-induced agglomeration of fine particles/droplets in aerosol is important in various industrial and natural processes. Despite abundant theoretical and numerical studies on turbulent collision kernels, convincing numerical methods for industry-scale applications are still lacking. In this work, we develop a mixed Eulerian-Lagrangian model for the modeling of turbulence-induced agglomeration of fine particles/droplets. As advantages over Sommerfeld's model, the present model searches for real collision pairs based on a new mesh-independent method and uses appropriate turbulent collision kernels to calculate the collision frequencies. Benchmark simulations are carried out and compared with the results provided by the well-characterized experiment by Duru et al.

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Experimental cloud droplet collection efficiencies

Cited by 20 publications

References 12 publications

A survey of Waterdrop Interaction Experiments

A survey of Waterdrop Interaction Experiments

An experimental investigation of the influence of electric field on the collision-coalescence of water drops

An industry-scale modeling for the turbulence agglomeration of fine particles

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