Analytical Consideration for the Maximum Spreading Factor of Liquid Droplet Impact on a Smooth Solid Surface

Langmuir ◽  
2021 ◽  
Author(s):  
Jiayu Du ◽  
Xiong Wang ◽  
Yanzhi Li ◽  
Qi Min ◽  
Xinxin Wu
Keyword(s):  
Solid Surface ◽  
Liquid Droplet ◽  
Droplet Impact ◽  
Spreading Factor ◽  
Analytical Consideration ◽  
Maximum Spreading

scholarly journals Pressure generated at the instant of impact between a liquid droplet and solid surface

2018 ◽  
Vol 5 (12) ◽  
pp. 181101 ◽  
Author(s):  
Y. Tatekura ◽  
M. Watanabe ◽  
K. Kobayashi ◽  
T. Sanada
Keyword(s):  
Solid Surface ◽  
Shape Factor ◽  
Liquid Droplet ◽  
Pressure Rise ◽  
Propagation Speed ◽  
Spherical Shape ◽  
Water Hammer ◽  
Droplet Impact ◽  
Maximum Pressure ◽  
The Impact

The prime objective of this study is to answer the question: How large is the pressure developed at the instant of a spherical liquid droplet impact on a solid surface? Engel first proposed that the maximum pressure rise generated by a spherical liquid droplet impact on a solid surface is different from the one-dimensional water-hammer pressure by a spherical shape factor (Engel 1955 J. Res. Natl Bur. Stand. 55 (5), 281–298). Many researchers have since proposed various factors to accurately predict the maximum pressure rise. We numerically found that the maximum pressure rise can be predicted by the combination of water-hammer theory and the shock relation; then, we analytically extended Engel’s elastic impact model, by realizing that the progression speed of the contact between the gas–liquid interface and the solid surface is much faster than the compression wavefront propagation speed at the instant of the impact. We successfully correct Engel’s theory so that it can accurately provide the maximum pressure rise at the instant of impact between a spherical liquid droplet and solid surface, that is, no shape factor appears in the theory.

Effect of Materials’ Wettability on the Dynamic Behavior of Droplet Impact onto a Rough Solid Surface

2011 ◽  
Vol 320 ◽  
pp. 341-346
Author(s):  
Jing Cui ◽  
Yang Liu ◽  
Wei Zhong Li ◽  
Ning Zhang
Keyword(s):  
Contact Angle ◽  
Solid Surface ◽  
Liquid Droplet ◽  
Droplet Impact ◽  
Apparent Contact Angle ◽  
Bottom Surface ◽  
Roughness Elements ◽  
Hydrophilic Material ◽  
Boltzmann Method ◽  
Intrinsic Contact Angle

In this paper, the effect of material’s wettability on the droplet impact has been investigated by numerical apporach. The unsteady flow behaviors of liquid droplet impacting against the rough solid surface with different wettabilities have been simulated based on lattice Boltzmann method. The spreading and bounding characterisitcs of droplet have been discussed. For the hydrophilic material, the droplet will sink into the grooves among roughness bumps, and its apparent contact angle in steady stead will be smaller than its corresponding intrinsic contact angle; while for the hydrophilic material, droplet will flow into the grooves but suspend on the top of roughness elements without any contacting with the bottom surface, and the apparent contact angle is larger than its intrinsic contact angle.

scholarly journals Study of the effect of surface wettability on droplet impact on spherical surfaces

2020 ◽  
Vol 15 (3) ◽  
pp. 414-420 ◽  
Author(s):  
Xiaohua Liu ◽  
Kaimin Wang ◽  
Yaqin Fang ◽  
R J Goldstein ◽  
Shengqiang Shen
Keyword(s):  
Contact Angle ◽  
Impact Velocity ◽  
Droplet Impact ◽  
Surface Wettability ◽  
Spreading Factor ◽  
Curvature Ratio ◽  
Spherical Surfaces ◽  
The Impact ◽  
Maximum Spreading ◽  
Effect Of Surface

Abstract The effect of surface wettability on droplet impact on spherical surfaces is studied with the CLSVOF method. When the impact velocity is constant, with the increase in the contact angle (CA), the maximum spreading factor and time needed to reach the maximum spreading factor (tmax) both decrease; the liquid film is more prone to breakup and rebound. When CA is constant, with the impact velocity increasing, the maximum spreading factor increases while tmax decreases. With the curvature ratio increasing, the maximum spreading factor increases when CA is between 30 and 150°, while it decreases when CA ranges from 0 to 30°.

scholarly journals Investigation of Dynamic Characteristics of Liquid Nitrogen Droplet Impact on Solid Surface

2022 ◽  
Vol 14 (2) ◽  
pp. 710
Author(s):  
Ke Zhao ◽  
Yang Ding
Keyword(s):  
Liquid Nitrogen ◽  
Solid Surface ◽  
Dynamic Characteristics ◽  
Wall Temperature ◽  
Spray Cooling ◽  
Droplet Impact ◽  
Spreading Factor ◽  
Normal Medium ◽  
The Common ◽  
Cooling Technology

Liquid nitrogen spray cooling technology exhibits excellent heat transfer efficiency and environmental protection performance. The promotion of this technology plays an important role in improving the sustainable development of the refrigeration industry. In order to clarify its complex microscale behavior, the coupled Level Set-VOF method was adopted to study the dynamic characteristics of liquid nitrogen droplet impact on solid surface in this paper. The spreading behaviors under various factors (initial velocity, initial diameter, wall temperature, and We number) were systematically analyzed. The results show that the spreading behaviors of liquid nitrogen droplet share the same process with the normal medium, which are rebound, retraction, and splashing. For the droplet with smaller velocity and diameter, Rebound is the common phenomenon due to the smaller kinetic energy. With the increase of droplet diameter (0.2 mm to 0.5 mm) and velocity (0.1 m/s to 5 m/s), the spreading factor increases rapidly and the spreading behaviors evolve into retraction and splashing. The increase of wall temperature accelerates the droplets spreading, and the spreading factor increases accordingly. For the liquid nitrogen droplets hit the wall, the dynamic behaviors of rebound (We < 0.2), retraction (0.2 < We < 4.9), and splashing (We > 4.9) will occur with the droplet weber number increased, which are consistent with the common medium. However, due to liquid nitrogen having lower viscosity and surface tension, the conditions of morphological transformations are different from the common media. The maximum spreading diameter has a power correlation with We, the power index of We is 0.306 for liquid nitrogen, lager than common medium (0.25). The reasons are: (1) the better wettability of liquid nitrogen, and (2) the vapor generated by the violent phase change ejects along the axial direction. The article will provide a certain theoretical basis for liquid nitrogen spray cooling technology, and can also enrich the flow dynamics of cryogenic fluids.

Numerical Investigation of Water Droplet Impact on Solid Surface in Microgravity

2013 ◽  
Vol 390 ◽  
pp. 65-70
Author(s):  
Jun Jun Tao ◽  
Jun Qin ◽  
Xue Han ◽  
Yong Ming Zhang
Keyword(s):  
Solid Surface ◽  
Water Droplet ◽  
Normal Gravity ◽  
Numerical Study ◽  
Liquid Droplet ◽  
Water Mist ◽  
Droplet Impact ◽  
Gravity Level ◽  
Vof Model ◽  
Fuel Vapour

A numerical study based on VOF model has been carried out to investigate the dynamics of water droplet impact on solid surface in microgravity in comparison with that in normal gravity to discuss the differences of the extinguishing mechanism of water mist in different gravity level. Water droplets with different initial diameters and impact velocities were considered. The simulated results show that the deformation process in microgravity lags behind that in normal gravity. And it was also found that Dmaxand spread velocities are smaller in microgravity as the potential energy decreases and the time taken for a liquid droplet to reach its maximum spread has no obvious regularity. Hence, the effect of cooling the fuel surface and diluting fuel vapour with water mist in microgravity may be not as good as that in normal gravity.The critical impact Weber number for water droplet breaking up in microgravity is lower than that in normal gravity as the reduction of the value of Bond number, which may result in diluting fuel vapour with water mist in microgravity being more effective than that in normal gravity in some case.

Hollow droplet impact on a solid surface

2021 ◽  
pp. 103740
Author(s):  
Mahdi Nasiri ◽  
Ghobad Amini ◽  
Christian Moreau ◽  
Ali Dolatabadi
Keyword(s):  
Solid Surface ◽  
Droplet Impact
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