Article
Mechanics
Yi-Feng Wang, Yi-Bo Wang, Xin He, Ben-Xi Zhang, Yan-Ru Yang, Xiao-Dong Wang, Duu-Jong Lee
Summary: This study investigates the dynamics of low-viscosity nanodroplets impacting surfaces with static contact angles, and obtains the morphologies and dominant forces at different spreading states. Scaling laws of spreading time and contact time are proposed, and an impact number is introduced to determine the importance of viscous force.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Anjan Goswami, Yannis Hardalupas
Summary: This study investigates the dynamics of the simultaneous impact of two droplets on a dry substrate. A new micro-controlled droplet generator is developed to release two equally sized water droplets simultaneously on-demand. The impact processes for both deposition and splashing of the liquid sheet are analyzed. Simultaneous high-speed imaging provides a quantification of the three-dimensional structure of the sheet morphology, including the temporal evolution of various features.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Physics, Fluids & Plasmas
Zhigang Xu, Tianyou Wang, Zhizhao Che
Summary: The study investigates the cavity deformation and bubble entrapment during the impact of droplets on a liquid pool, finding that gravity and environmental pressure play crucial roles in these phenomena. As gravity becomes stronger, the maximum depth of the cavity decreases, and the phenomenon of regular bubble pinch-off may disappear. Increasing environmental pressure can transform regular bubble pinch-off into large bubble entrapment. The size of the large bubble entrapped decreases with increasing environmental pressure due to differences in pressure and vorticity. Finally, a regime map of bubble entrapment after droplet impact is obtained.
Article
Mechanics
Zhenlong Wu, Yihua Cao, Yufeng Yao
Summary: This paper dissects the complex process of air bubble formation when a drop impacts on a solid surface through direct numerical simulation. Detailed quantitative analysis is performed and new insights are proposed regarding the physical mechanisms associated with the evolution of the entrapped air film.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2021)
Article
Chemistry, Multidisciplinary
Ming Li, Huaizhen Yang, Junjian Wang, Gang Li, Jiao Tang
Summary: This study investigates the influence of surface tension and viscosity on the atomization performance of solid cone nozzles and proposes ways to improve dust reduction efficiency in industrial and mining enterprises. The experimental results show that surface tension has a greater impact on droplet size and velocity in the axial direction, while increasing surface tension and reducing viscosity within a certain range can result in a more uniform distribution in the radial direction. Surface tension and viscosity also play a significant role in fog field distribution, with a decrease in surface tension bringing the droplet velocity and size expansion area closer to the nozzle, and an increase in viscosity leading to a more prolonged stable area. Optimizing surface tension and viscosity can greatly enhance the efficacy of dust reduction for respirable dust.
APPLIED SCIENCES-BASEL
(2023)
Article
Mechanics
Sungchan Yun
Summary: This study investigates the impact dynamics of ellipsoidal drops on nonwetted solid surfaces, showing that reducing the bounce magnitude can be achieved by changing the impact angle and ellipticity. Experimental and numerical studies demonstrate that ellipsoidal drops exhibit a significant reduction in maximum bounce height compared to spherical drops, with oblique drop impacts leading to off-axis aligning processes caused by asymmetric retraction dynamics.
Article
Chemistry, Multidisciplinary
Fan Xiao, Kai Li, Wei Wang, Yuntong Ge, Zhipeng Yu, Zeheng Peng, Yingming Liu, Jing Gong
Summary: The stabilization mechanism of water-in-oil emulsions was studied using atomic force microscopy to measure the interactions between water droplets in n-tetradecane. The addition of oil-soluble surfactants (Span 20) was found to prevent water droplet coalescence by adsorbing onto the interface and forming a tight layer. The presence of water-soluble surfactants (SDS/CTAB/Tween 80) had varying effects on droplet stability, with Tween 80 destabilizing the droplets due to competitive adsorption with Span 20.
Article
Mechanics
Sayali N. Jadhav, Uddipta Ghosh
Summary: The study investigates the effect of surfactants on drop settling dynamics, finding that surfactants can alter the settling speed and deformation of the drops, with the most significant effects near the solid wall.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Chemistry, Physical
Yuxuan Du, Ji Liu, Yanzhi Li, Jiayu Du, Xinxin Wu, Qi Min
Summary: This study investigates the dynamics of droplet impact on spherical surfaces at various Reynolds and Weber numbers using the phase-field method. It explores the temporal evolution of spreading factor and dimensionless center thickness, and concludes that different forces dominate in different regimes. The study also proposes prediction models for the exponents a, b, and c, which are strongly related to the diameter ratio of spheres and droplets.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2021)
Article
Construction & Building Technology
Jian Ouyang, Yan Meng
Summary: The quantitative effects of droplet size and emulsion viscosity on the storage stability of asphalt emulsion were studied. A model relating the storage stability to the droplet size and emulsion viscosity was proposed, and prediction models for the 1 day and 5 day storage stability were established. The results indicated that droplet diameter and emulsion viscosity were highly correlated with the storage stability. The proposed prediction equations can estimate the storage stability accurately and quickly.
CONSTRUCTION AND BUILDING MATERIALS
(2022)
Article
Mechanics
Tongwei Zhang, Jie Wu, Xingjian Lin
Summary: This study investigates the dynamic mechanisms and factors influencing the lateral motion of a solid when impacted by a water droplet on a movable hydrophobic substrate. The experimental results reveal the rules governing the solid's motion and demonstrate the possibility of achieving periodic reciprocating motion under suitable conditions.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Mahdi Nasiri, Ghobad Amini, Christian Moreau, Ali Dolatabadi
Summary: In this study, the spreading process of a hollow droplet impacting a rigid surface is investigated through experimental, numerical, and theoretical methods. Numerical simulations successfully predict the shape evolution of the hollow droplet, which is validated by experimental photographs. The results demonstrate that the spreading diameter and height of the hollow droplet increase with impact velocity. Additionally, an optimal bubble size is identified to facilitate the flattening process, and it is found that the ripples on the splats produced by larger bubbles are higher. A theoretical model is developed, which accurately predicts the maximum spreading diameter and agrees well with experimental and numerical results.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Physics, Fluids & Plasmas
Saurabh Nath, David Quere
Summary: In this article, the spreading process of water droplets on liquid-infused solids (LISs) is investigated. It is found that despite the lubrication effect, the spreading of water droplets on LIS is slower compared to bare solids, even at short times. This phenomenon can be explained by considering the friction in the film, indicating that the slippery nature of LISs can be accompanied by significant dissipation.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Chemistry, Multidisciplinary
Huy-Hong-Quan Dinh, Enric Santanach-Carreras, Marie Lalanne-Aulet, Veronique Schmitt, Pascal Panizza, Francois Lequeux
Summary: By conducting experiments, we determined the coalescence rates of water droplets within emulsions stabilized by Span 80 in the presence of Tween 20. Using a microscopic model based on a theory of hole nucleation, we established an analytical formula that quantitatively predicts the coalescence frequency. Despite its simplicity and assumptions, this formula accurately captures experimental results in a wide range of water-in-crude oil systems.
Article
Mechanics
Jiangxu Huang, Lei Wang, Junjie Hu
Summary: This paper numerically investigates the droplet impact dynamics on Janus-textured heated substrates. Three distinct boiling regimes are observed and the effects of control parameters on droplet behavior are analyzed.
Article
Thermodynamics
Amrit Kumar, Deepak Kumar Mandal
HEAT AND MASS TRANSFER
(2020)
Article
Automation & Control Systems
Amit Kumar, Amitava Mandal, Amit Rai Dixit, Deepak Kumar Mandal
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2020)
Article
Chemistry, Physical
Lukesh Kumar Mahato, Deepak Kumar Mandal
Summary: When a droplet is in motion, resisting shear increases with viscosity and velocity, compared to adhesion, regardless of surface wettability. The total shear, with wedge shear being higher than bulk shear, is found to decrease with lower viscosity and higher velocity drops at a given Weber number.
COLLOID AND INTERFACE SCIENCE COMMUNICATIONS
(2021)
Article
Thermodynamics
Vikas Kumar, Amrit Kumar, Deepak Kumar Mandal
Summary: Straight vegetable oils have the potential to reduce dependence on conventional fossil fuels, and the study found that impact velocity and surface temperature affect the spreading and receding of oil drops on stainless steel surfaces. The research showed that the minimum surface temperature and average receding velocity are independent of Weber number and initial kinetic energy, with the highest receding velocity observed at 280 degrees Celsius.
HEAT TRANSFER ENGINEERING
(2022)
Article
Thermodynamics
Amrit Kumar, Deepak Kumar Mandal
Summary: The impact of water-in-Jatropha biodiesel emulsion drops on a heated solid surface is influenced by internal vapor pressure and thin vapor film formation, affecting sticking and bouncing behavior. The spreading and receding velocities of emulsions increase with surface temperature, with differences observed in impact morphology compared to JBD. The internal vapor pressure in emulsions at higher temperatures results in a higher maximum spreading factor and spreading velocity than JBD.
HEAT AND MASS TRANSFER
(2022)
Article
Chemistry, Multidisciplinary
Ramesh Kumar Singh, Lukesh Kumar Mahato, Deepak Kumar Mandal
Summary: The role of liquid viscosity on the spreading of drops on a surface under the influence of airflow has been investigated. The spreading diameter is found to increase with the Reynolds number of the airflow and the impact Weber number, contributing factors being additional air pressure and shear forces. As the drops spread, their curvature decreases, and large-scale eddies are observed near the drop-surface region.
Article
Mechanics
Lukesh Kumar Mahato, Deepak Kumar Mandal
Summary: The deformation of oil drops during waterflow recovery from surfaces is examined experimentally and numerically. The behavior of waterflow during the deformation is observed to be consistent in both approaches. The deformation of the drops is influenced by the water shear flow velocity and the nature of the surface.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2022)
Article
Thermodynamics
Vikas Kumar, Deepak Kumar Mandal
Summary: This study investigates the impact of different Jatropha - diesel blend drops on a surface by varying the surface temperature and Weber number. The results show that drop viscosity and density play critical roles, and the maximum spread, average spreading velocity, and recoiling intensity of a drop are influenced by both surface temperature and Weber number. Furthermore, the viscosity and density decrease with the increase in diesel content, leading to an increase in spreading. The changes in viscosity and density also affect the drop's energy dissipation and inertia during spreading. Therefore, incorporating the variations of viscosity and density with surface temperature into existing models can accurately predict the maximum spread.
HEAT TRANSFER ENGINEERING
(2023)
Article
Mechanics
Aadil Kureshee, S. Narayanan, Deepak Kumar Mandal
Summary: This study investigates the impact of an acoustic field on evaporation and internal circulation of twin drops with varying horizontal spacing. The results show that the maximum evaporation rate and circulation occur at the lowest frequency and highest spacing. The evaporation rate increases with spacing up to a critical distance, beyond which it becomes nearly identical. The spacing, evaporation rate, and outer flow velocity are found to be correlated. The perception that any acoustic wave enhances evaporation is proven incorrect, as the evaporation and circulation decline with increasing frequency.
Article
Engineering, Multidisciplinary
Amrit Kumar, Deepak Kumar Mandal
Summary: The impact dynamics of water-in-Jatropha biodiesel compound drops on a solid surface change interestingly with the increase in volume fraction, including the increase in spreading factor and the appearance of receding.
ATOMIZATION AND SPRAYS
(2022)
Article
Engineering, Multidisciplinary
Amrit Kumar, Deepak Kumar Mandal
Summary: The study found that water and JBD drops disintegrate upon impact on an inclined surface, while emulsions do not. Additionally, the residence time T-R is directly related to the total sliding distance S-T of the drop over the surface, and both are affected by the percentage of water in the emulsion.
ATOMIZATION AND SPRAYS
(2021)
Proceedings Paper
Engineering, Mechanical
Amrit Kumar, Abhishek Singh, Deepak Kumar Mandal
ADVANCES IN MECHANICAL ENGINEERING, ICRIDME 2018
(2020)
