Turbulence-induced cloud voids: observation and interpretation

Abstract. The phenomenon of “cloud voids”, i.e., elongated volumes inside a cloud that are devoid of droplets, was observed with laser sheet photography in clouds at a mountain-top station. Two experimental cases, similar in turbulence conditions yet with diverse droplet size distributions and cloud void prevalence, are reported. A theoretical explanation is proposed based on the study of heavy inertial sedimenting particles inside a Burgers vortex. A general conclusion regarding void appearance is drawn from theoretical analysis. Numerical simulations of polydisperse droplet motion with realistic vortex parameters and Mie scattering visual effects accounted for can explain the presence of voids with sizes similar to that of the observed ones. Clustering and segregation effects in a vortex tube are discussed for reasonable cloud conditions.

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Turbulence Induced Cloud Voids: Observation and Interpretation

10.5194/acp-2018-1049 ◽

2018 ◽

Author(s):

Katarzyna Karpińska ◽

Jonathan F. E. Bodenschatz ◽

Szymon P. Malinowski ◽

Jakub L. Nowak ◽

Steffen Risius ◽

...

Keyword(s):

Vortex Tube ◽

Laser Sheet ◽

Mie Scattering ◽

Theoretical Explanation ◽

Size Distributions ◽

Visual Effects ◽

Droplet Motion ◽

Preferential Concentration ◽

Burgers Vortex ◽

Droplet Size Distributions

Abstract. The phenomenon of cloud voids, i.e., elongated volumes inside a cloud that are devoid of droplets, was observed with laser sheet photography in clouds at a mountain-top station. Two experimental cases, similar in turbulence conditions yet with diverse droplet size distributions and cloud void prevalence, are reported. A theoretical explanation is proposed based on the study of heavy inertial sedimenting particles inside a Burgers vortex. A general conclusion regarding void appearance is drawn from theoretical analysis. Numerical simulations of polydisperse droplet motion with realistic vortex parameters and Mie scattering visual effects accounted for can explain the presence of voids with sizes similar to that of the observed ones. Preferential concentration and sorting effects in a vortex tube are discussed for reasonable cloud conditions.

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Experimental and Simulation of Kinematics of Multi-Droplet of Emulsion under Electric Field

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.94-96.1675 ◽

2011 ◽

Vol 94-96 ◽

pp. 1675-1680

Author(s):

Chang Yong Wang ◽

Huan Qun Qian

Keyword(s):

Electric Field ◽

Droplet Size ◽

High Speed ◽

Electric Field Intensity ◽

Integration Method ◽

Ccd Camera ◽

Size Distributions ◽

Droplet Motion ◽

Lagrangian Framework ◽

Droplet Size Distributions

Experiments have been performed to observe the kinematics of multi-droplet moving in a stationary emulsion exposed to a horizontal electric field of different magnitude. The droplet motion is recorded by a high-speed CCD camera. A Lagrangian framework is outlined to simulate the kinematics of multi-droplet by means of cluster integration method. The droplet size distributions computed are qualitatively consistent with the experimental picture. It is clarified from computation that the effect of the electric field intensity and the viscosity of the oil on the droplet motion. Experiments have been performed to observe the kinematics of multi-droplet moving in a stationary emulsion exposed to a horizontal electric field of different magnitude. The droplet motion is recorded by a high-speed CCD camera. A Lagrangian framework is outlined to simulate the kinematics of multi-droplet by means of cluster integration method. The droplet size distributions computed are qualitatively consistent with the experimental picture. It is clarified from computation that the effect of the electric field intensity and the viscosity of the oil on the droplet motion.

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