Article
Engineering, Chemical
Jun Yin, Simon Kuhn
Summary: Due to the dominance of interfacial forces, microreactors are widely used in multiphase processes where control over the dispersed phase volume is crucial. Therefore, accurately predicting droplet breakup and the resulting two-phase flow pattern using computational tools is important in the design of such microfluidic devices. This study demonstrates that integrating a dynamic contact angle model into a volume-of-fluid (VOF) solver significantly improves the accuracy of droplet formation prediction in a microfluidic T-junction compared to earlier studies with a constant contact angle model. Additionally, it was found that the advancing contact angle has a greater influence on droplet formation compared to the receding contact angle. These findings confirm that using a dynamic contact angle model with a VOF approach in simulating droplet formation in microchannels will lead to more accurate predictions.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Engineering, Chemical
Zhi-Hao Liu, Yan-Bin Li, Meng-Jun Su, Yong Luo, Guang-Wen Chu
Summary: This study investigated the dispersion phenomena of liquid droplets impacting on fibers with different wettability through experiments and simulations. Three flow patterns were observed, and four contact angle models were implemented. The results showed that the gas-liquid interfacial area and energy utilization efficiency increased significantly with the increase of the contact angle.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Energy & Fuels
Bifeng Yin, Sheng Xu, Hekun Jia, Fei Dong
Summary: A novel dynamic contact angle model is introduced in this study. A two-dimensional model of water droplet impact is established, and the influences of equilibrium contact angle, sliding angle, and velocity are explored. The results show that when droplets impact the channel surface, they exhibit spreading, rebounding, and moving states.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2022)
Review
Chemistry, Physical
Junheng Ren, Fei Duan
Summary: The review focuses on sessile droplet wetting behaviors on structured substrates, covering recent experimental advances in wetting on hydrophobic, hydrophilic, or combined hydrophobic and hydrophilic surfaces. Attention is given to the wetting configuration and three-phase line shape identification, with potential for new physical insights through three-dimensional measurements on patterned surfaces.
CURRENT OPINION IN COLLOID & INTERFACE SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Ghokulla Haran Krishnan, Kevin Fletcher, Eric Loth
Summary: This study investigates the effects of liquid viscosity and surface wettability on the outcomes of a droplet impacting a dry, clean surface. Through a series of experiments, six different outcomes were observed and several trends were identified.
Article
Chemistry, Physical
Yihang Xiao, Jun Zheng, Yongming He, Lei Wang
Summary: Droplet and bubble wetting behaviors have significant differences, and surface roughness affects the wetting behaviors. The study reveals a critical Young contact angle for bubble wetting, above which apparent contact angle and contact angle hysteresis abruptly change. Increased roughness reduces bubble apparent contact angle and contact angle hysteresis.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2022)
Article
Chemistry, Analytical
Yukihiro Yonemoto, Yosuke Fujii, Yoshiki Sugino, Tomoaki Kunugi
Summary: This study investigates the sliding behavior of water-ethanol mixture droplets on an inclined solid surface through experimental observation. The study finds that the size of the droplet affects its adhesion property, with larger droplets experiencing increased adhesion force while smaller droplets maintain a constant force. This difference is related to the degree of droplet shape deformation.
Article
Chemistry, Physical
Amir Azimi Yancheshme, Giuseppe R. Palmese, Nicolas J. Alvarez
Summary: This work presents a generalized solution for the spontaneous spreading dynamics of droplets, taking into account the influence of interfacial tension and gravity. The authors validate and modify a dynamic contact angle model to accurately describe the dependency of contact angle on the contact line velocity. This model is then implemented into a computational fluid dynamics (CFD) model, which is validated using experimental results.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Yuming Yin, Lingling Zhao, Shangchao Lin
Summary: Using molecular dynamics simulations, this study investigates the wetting characteristics of CO2 on smooth and rough surfaces. The results show that the contact angle of CO2 droplets decreases on smooth surfaces with increasing CO2-solid interaction energy, while it increases on rough surfaces with higher surface roughness. The study also uncovers the capillary drying-out phenomenon of CO2 molecules at the three-phase contact line of the droplets, which has been overlooked in previous theoretical studies.
Article
Mechanics
Yanling Chen, Liang Guo, Wanchen Sun, Ningning Cai, Yuying Yan
Summary: This study investigates the effects of surface wettability and rough structure on the wetting behavior of fuel droplets after hitting the walls using molecular dynamics method. The results show that a decrease in the solid-liquid interaction coefficient leads to an increase in the static contact angle and rough surface structures inhibit the spreading of the droplets. Additionally, specific boss-shaped structures enhance the surface oleophobicity.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2023)
Article
Ecology
David Dunkerley
Summary: This study describes a low-cost, electro-mechanical tilting table to measure leaf wetting and drainage characteristics of different taxa. The experiment on Homolanthus populifolius reveals complex behavior in which the open leaf surface is hydrophobic but major adaxial veins are strongly hydrophilic and can trap droplets. The apparent droplet roll-off angles are dependent on the tilt speed applied.
METHODS IN ECOLOGY AND EVOLUTION
(2023)
Article
Thermodynamics
Lingyi Guo, Li Chen, Ruiyuan Zhang, Ming Peng, Wen-Quan Tao
Summary: This study proposes a pore-scale model based on the lattice Boltzmann method to investigate the effects of oxygen transport and water flooding in gas diffusion layer (GDL) on proton exchange membrane fuel cell performance. The model considers two-phase flow, oxygen diffusion, and electrochemical reaction in the GDL. The results show that reducing total saturation in the GDL is important, but decreasing local saturation near the microporous layer (MPL)/GDL interface is crucial for enhancing cell performance. Additionally, enhancing hydrophobicity at the MPL/GDL interface or gradually increasing GDL porosity from bottom to top can improve cell performance significantly.
Article
Chemistry, Physical
Qiaoyu Guo, Yanzhou Qin
Summary: This study investigates the effects of novel channel designs on liquid water removal in PEMFC, compared to traditional straight channels. The one-block channel accelerates water movement but with higher pressure drop, while the separated two-block channel achieves faster water removal and smaller pressure drop through capillary wicking effect.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Energy & Fuels
Yulin Wang, Han Wang
Summary: This paper investigates the dynamic characteristics of water droplet detachment from a rough gas diffusion layer (GDL) surface and finds that the gas velocity, space distance, and wettability of cubic pillars significantly affect the detachment process. On a highly hydrophilic surface, the water droplet detaches quickly regardless of spatial distance and gas velocity. On a moderately hydrophilic GDL, a larger space distance benefits droplet detachment. On a highly hydrophobic GDL, a larger space distance and higher gas velocity facilitate droplet detachment.
Article
Chemistry, Physical
Sreya Sarkar, Tamal Roy, Ankit Roy, Shashwata Moitra, Ranjan Ganguly, Constantine M. Megaridis
Summary: This study investigates the impact of surface roughness on contact angle measurements through experiments and theoretical models. As the surface roughness increases, the dynamic contact angles measured by different methods deviate from the supplementary principle. A theoretical explanation is provided for this disparity, with predictions based on prevalent thermodynamic models of wetting and contact-angle hysteresis on rough substrates.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2021)
