Effect of Large Amplitude Waves and Film Inertia on Mass Separation at a Sharp Corner

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Zahra Sadeghizadeh ◽  
James A. Drallmeier
Keyword(s):  
Liquid Film ◽  
Gas Phase ◽  
Large Amplitude ◽  
Thin Liquid Film ◽  
Mass Separation ◽  
Sharp Corner ◽  
Film Substrate ◽  
The Impact ◽  
Separation Results ◽  
Insight Into

The separation of a shear-driven thin liquid film from a sharp corner is studied in this paper. Partial or complete mass separation at a sharp corner is affected by two different mechanisms: liquid film inertia, which affects liquid mass separation through force imbalance at the sharp corner, and large amplitude waves (LAW) at the interface, which contributes to liquid instability at the corner. Experimental results for liquid Ref number that varies from 100 to 300 and mean film thickness from 130 to 290 μm show that both film inertia and LAW effects correlate to mass separation results. The results suggest that while both inertia of the film substrate and LAW effects enhance the mass separation, the correlations between LAW characteristics and mass separation results provide better insight into the onset of separation and the impact of the gas phase velocity on separation for the conditions studied.

The Impact of Bubble Dynamic Behaviors on Liquid Film in Open Capillary Microgrooves

2011 ◽  
Author(s):  
Yang Cao ◽  
Xuegong Hu ◽  
Dawei Tang ◽  
Chaohong Guo ◽  
Xuelei Nie
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Contact Line ◽  
Thin Liquid Film ◽  
Maximum Speed ◽  
Phase Contact ◽  
Bubble Dynamic ◽  
Dynamic Behaviors ◽  
Liquid Drops ◽  
The Impact

In this paper, the characteristics of bubble dynamic behaviors and the impacts on the triple-phase contact line are studied by a visualization investigation. A high-speed digital camera with maximum speed of 30000 frames per second is adopted to record the period of bubble growth and the geometry of the splashed liquid drops. The information of the bubble dynamic behavior and the liquid drops volume can be analyzed through the software MATLAB. The statistics of the splashed liquid drops is adopted under different heat flux conditions. The experimental results show that the bubble dynamic behaviors lead to the fluctuation of the triple-phase contact line and the splashed liquid drops make the heat transfer capability of the film in microgrooves less than its theoretical maximum value. The investigation indicates that the bubble behaviors can influence the performance of heat transfer through the fluctuations of the triple-phase contact line in the thin liquid film in microgrooves. And the splashed liquid drops appearing in boiling process can also affect the heat transfer of the liquid film in open capillary microgrooves.

Insights on the impact of a plane drop on a thin liquid film

2011 ◽  
Vol 23 (2) ◽  
pp. 022105 ◽  
Author(s):  
Gennaro Coppola ◽  
Giuseppe Rocco ◽  
Luigi de Luca
Keyword(s):  
Liquid Film ◽  
Thin Liquid Film ◽  
The Impact

scholarly journals The Low-Temperature Ring during Droplet Impact on a Superhydrophilic Surface

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1043
Author(s):  
Huixia Ma ◽  
Jiang Chun ◽  
Feng Zhou ◽  
Kai Qiao ◽  
Rui Jiang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Liquid Film ◽  
Thin Liquid Film ◽  
Film Surface ◽  
Industrial Applications ◽  
Droplet Impact ◽  
Functional Coatings ◽  
Superhydrophilic Surface ◽  
The Impact

Droplet impact on the solid surfaces is widespread in nature, daily life, and industrial applications. The spreading characteristics and temperature evolution in the inertial spreading regime are critical for the heat and mass transfer process on the solid-liquid interface. This work investigated the spreading characteristics and temperature distribution of the thin liquid film in the inertial rapid spreading regime of droplet impact on the heated superhydrophilic surfaces. Driven by the inertial and capillary force, the droplet rapidly spreads on the superhydrophilic surface, resulting in a high temperature center in the impact center surrounded by a the low-temperature ring. The formation of the unique the low-temperature ring on the heated superhydrophilic surface is due to the much smaller time scale of rapid spreading than that of heat transfer from the hot solid surface to the liquid film surface. CFD numerical simulation shows that the impacting droplet spreads and congests in the front of liquid film, leading to the formation of vortex velocity distribution in the liquid film. Increasing We number and wall temperature can accelerate the heat transfer rate of liquid film and shorten the existence time of the low-temperature ring. The findings of the the low-temperature ring on the superhydrophilic surface provide the guidelines to optimization of surface structures and functional coatings for enhancing heat transfer in various energy systems.

scholarly journals Characteristics of Splash Formed by the Impact of Liquid Jet on a Thin Liquid Film

2020 ◽  
Vol 1549 ◽  
pp. 032028
Author(s):  
Tianyu Kang ◽  
Qin Qin ◽  
Xin Yao ◽  
Qingbo Yu
Keyword(s):  
Liquid Film ◽  
Thin Liquid Film ◽  
Liquid Jet ◽  
The Impact

A Separation Criterion With Experimental Validation for Shear-Driven Films in Separated Flows

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
M. A. Friedrich ◽  
H. Lan ◽  
J. L. Wegener ◽  
J. A. Drallmeier ◽  
B. F. Armaly
Keyword(s):  
Liquid Film ◽  
Gas Phase ◽  
Experimental Validation ◽  
Thin Liquid Film ◽  
Complete Separation ◽  
Separated Flows ◽  
Force Ratio ◽  
Wide Range ◽  
Inertial Surface ◽  
Film Separation

The behavior of a shear-driven thin liquid film at a sharp expanding corner is of interest in many engineering applications. However, details of the interaction between inertial, surface tension, and gravitational forces at the corner that result in partial or complete separation of the film from the surface are not clear. A criterion is proposed to predict the onset of shear-driven film separation from the surface at an expanding corner. The criterion is validated with experimental measurements of the percent of film mass separated as well as comparisons to other observations from the literature. The results show that the proposed force ratio correlates well to the onset of film separation over a wide range of experimental test conditions. The correlation suggests that the gas phase impacts the separation process only through its effect on the liquid film momentum.

scholarly journals Droplet impact on a thin liquid film: anatomy of the splash

2016 ◽  
Vol 802 ◽  
pp. 775-805 ◽  
Author(s):  
Christophe Josserand ◽  
Pascal Ray ◽  
Stéphane Zaleski
Keyword(s):  
Reynolds Number ◽  
Liquid Film ◽  
Numerical Simulations ◽  
Thin Liquid Film ◽  
Droplet Impact ◽  
The Other ◽  
Dimensionless Number ◽  
Scaling Analysis ◽  
The Impact ◽  
Short Times

We investigate the dynamics of drop impact on a thin liquid film at short times in order to identify the mechanisms of splash formation. Using numerical simulations and scaling analysis, we show that it depends both on the inertial dynamics of the liquid and the cushioning of the gas. Two asymptotic regimes are identified, characterized by a new dimensionless number $J$: when the gas cushioning is weak, the jet is formed after a sequence of bubbles are entrapped and the jet speed is mostly selected by the Reynolds number of the impact. On the other hand, when the air cushioning is important, the lubrication of the gas beneath the drop and the liquid film controls the dynamics, leading to a single bubble entrapment and a weaker jet velocity.

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