Article
Chemistry, Multidisciplinary
Calvin Thenarianto, Xue Qi Koh, Marcus Lin, Ville Jokinen, Dan Daniel
Summary: A water droplet can rebound multiple times on superhydrophobic surfaces, and the energy loss during such rebounds depends on the ratio of rebound speed to initial impact speed. We conducted experiments on different superhydrophobic surfaces with droplets of various sizes and proposed scaling laws to explain the nonmonotonic relationship between the energy loss and impact speed. At low impact speeds, the energy loss is influenced by contact-line pinning and the surface wetting properties, while at high impact speeds, it is dominated by inertial-capillary effects.
Article
Chemistry, Multidisciplinary
Jiawang Cui, Tianyou Wang, Zhizhao Che
Summary: In this experimental study, the melting process of frozen droplets on superhydrophobic surfaces was investigated. Two different melting morphologies with opposite vortex directions were observed, and the occurrence of Marangoni convection and natural convection in the melting droplets was confirmed through visualization and flow field measurements. The results provide important insights for understanding the melting process of frozen droplets and designing novel icephobic surfaces.
Article
Chemistry, Multidisciplinary
Shaur Humayun, R. Daniel Maynes, Julie Crockett, Brian D. Iverson
Summary: The present study investigates the retention forces between drops and superhydrophobic surfaces by measuring the contact angle distribution and base area shapes of drops on inclined microstructured superhydrophobic surfaces. The results show that using a sigmoid contact angle distribution and modified base area shape yields better retention forces compared to previous methods. The findings provide insights into the dynamics of drops on superhydrophobic surfaces and have implications for predicting heat transfer rates during dropwise condensation.
Letter
Mechanics
S. Tonini, G. E. Cossali
Summary: This paper presents an analytical/numerical study on the evaporation characteristics of deformed sessile drops on superhydrophobic substrates under the influence of the gravity field. The study systematically analyzes the effect for various contact angles and drop volumes, and quantifies the impact of drop deformation on evaporation rate. The paper also introduces a simple correlation as a correction to the existing model for non-deformed drops, providing a quick evaluation of evaporation rates for sessile drops on superhydrophobic substrates under gravitational influence.
Article
Mechanics
Lei Xing, Shuai Guan, Minghu Jiang, Longlong Shi
Summary: In this study, the directional transportation of droplets on a surface with controllable wettability was investigated numerically. The mechanisms of directional migration and morphological evolution of droplets impacting on the superhydrophobic-hydrophobic interface were revealed, and the effects of the impacting position on the migration velocity, rebound height, and transport distance of droplets were analyzed. Theoretical models were derived for predicting the transport distance and rebound height of droplets. The simulation results showed different stages in the process of droplet impacting on the superhydrophobic-hydrophobic interface compared to a normal surface. The study also found the existence of an optimal adhesion length for maximizing the transport distance of the droplet. The results contribute to the fundamental theory of droplet directional migration and have practical applications.
Article
Chemistry, Multidisciplinary
Mehdi H. Biroun, Luke Haworth, Hossein Abdolnezhad, Arash Khosravi, Prashant Agrawal, Glen McHale, Hamdi Torun, Ciro Semprebon, Masoud Jabbari, Yong-Qing Fu
Summary: Droplet impact behavior on solid surfaces is crucial for industrial applications such as spray coating, food production, printing, and agriculture. The challenge lies in modifying and controlling the impact regime and contact time of the droplets, which becomes more critical for non-Newtonian liquids. This study explores the impact dynamics of non-Newtonian liquids on superhydrophobic surfaces and shows that the addition of Xanthan alters the shape and reduces the contact time of the droplets.
Article
Mechanics
Minyoung Kim, Eungjun Lee, Do Hyun Kim, Rhokyun Kwak
Summary: This study reveals the unique behaviors of viscoplastic drops on an inclined superhydrophobic surface, including decoupled rolling, sliding, and sticking motions, as well as two distinct rolling modes: viscous rolling and rigid-body rolling. The research indicates that viscoplastic drops exhibit different rolling behaviors based on factors like gravitational, yield, and adhesive stresses. Furthermore, the study categorizes rolling into liquid-like viscous rolling and solid-like rigid-body rolling modes, showing that viscoplastic drops deform and tumble differently on inclined surfaces depending on their Deborah number.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Chemistry, Multidisciplinary
Chunfang Guo, Lei Liu, Rui Yang, Jiangtao Lu, Senyun Liu
Summary: Superhydrophobic surfaces have significant potential for passive anti-icing applications by reducing the contact time between droplets and surfaces. However, their anti-icing performance against supercooled water droplets has not been studied. We fabricated typical post-array and flat superhydrophobic surfaces to investigate the droplet impact dynamics. The contact time and bouncing behavior were systematically studied under controlled temperature, humidity, and surface frost conditions.
Article
Multidisciplinary Sciences
Abbasali Abouei Mehrizi, Shiji Lin, Lijie Sun, Yile Wang, Longquan Chen
Summary: The addition of high molecular weight polymer stabilizes droplets on superhydrophobic wire meshes, suppressing their spray behavior. Penetrated ligaments retract and merge with droplets on the mesh, and their evolution follows the Kelvin-Voigt model. The additive polymer also alters the recoil penetration mechanism.
SCIENTIFIC REPORTS
(2022)
Article
Chemistry, Multidisciplinary
Bhaskarjyoti Sarma, Dipankar N. Basu, Amaresh Dalal
Summary: The dynamics of liquid jets generated by droplet impact on a fractal superhydrophobic surface were investigated. Two different regimes of jets, singular and columnar, were observed depending on the impact conditions. Singular jets were formed at lower impact velocities and low viscosity, with a maximum velocity up to 20 times higher than the impact velocity. Cylindrical air cavities within the droplet played a crucial role in the formation of high-speed singular jets. In contrast, columnar jets were generated through capillary wave focusing at moderate to high impact velocities. The size of columnar jet drops varied nonmonotonically and was influenced by the preceding jetting dynamics. Both singular and columnar jetting events were suppressed at very high viscosities. These findings have implications for various technologies such as microdispensing, thermal management, and disease transmission.
Article
Chemistry, Multidisciplinary
Lizhong Wang, Guochen Jiang, Ze Tian, Changhao Chen, Xinyu Hu, Rui Peng, Hongjun Zhang, Peixun Fan, Minlin Zhong
Summary: Based on geometrical characteristics, surface microstructures can be categorized into closed-cell and open-cell structures. Closed-cell structures are known to have stable superhydrophobicity at room temperatures, but their anti-icing performance in low-temperature environments has not been confirmed. In this study, we used an ultrafast laser to fabricate superhydrophobic surfaces with tunable micro-nanostructures and found that open-cell structures exhibit better recovery and lower ice adhesion strengths compared to closed-cell structures.
MATERIALS HORIZONS
(2023)
Article
Chemistry, Multidisciplinary
Yaxun Fan, Yilin Wang
Summary: Deposition and spread of aqueous droplets on hydrophobic/superhydrophobic surfaces, which are important in practical applications such as spraying, coating, and printing, have been achieved by surfactants. However, the effects on superhydrophobic substrates have rarely been explored. This study gives an overview of the influence factors on the deposition and spreading performance and emphasizes the effects of fast surfactant aggregation.
Article
Chemistry, Physical
Diego Diaz, Diana Garcia-Gonzalez, Pravash Bista, Stefan A. L. Weber, Hans-Jurgen Butt, Amy Stetten, Michael Kappl
Summary: When neutral water drops impact and rebound from superhydrophobic surfaces, they acquire a positive electrical charge. The maximum contact area is identified as the dominant control parameter for charge separation.
Article
Mechanics
Ye Tian, Hong Wang, Xin Zhou, Zhenting Xie, Xun Zhu, Rong Chen, Yudong Ding, Qiang Liao
Summary: The impinging dynamic of a droplet on a superhydrophobic substrate in an electric field is investigated through visualization experiments and numerical simulations. Four ejection modes and three rebound modes are experimentally observed, and the filamentous ejecting phenomenon is discovered for the first time. The numerical simulation reveals the strong coupling between the distribution of electric charge and the evolution of droplet profile, and proposes a charge scaling law for ejection droplets. The results provide important characteristics for droplet manipulation and electrostatic spraying, and have implications for the design and operation of droplet equipment.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
S. L. Butler
Summary: The shapes of rotating fluid drops held together by surface tension are an important field of study in fluid mechanics. Comparisons between superfluid droplets and classical analogs have proven useful. Moreover, it has been found that off-axis inner drops with higher density will move towards the outer boundary.
Article
Environmental Sciences
Olfa Beji, Nouceiba Adouani, Souhila Poncin, Moktar Hamdi, Huai Z. Li
ENVIRONMENTAL TECHNOLOGY
(2020)
Article
Engineering, Chemical
Xiaofeng Jiang, Enle Xu, Guoguang Wu, Huai Z. Li
CHEMICAL ENGINEERING SCIENCE
(2020)
Article
Engineering, Chemical
Marco Scala, Lionel Garnet, Louis-Marie Malbec, Huai-Zhi Li
CHEMICAL ENGINEERING SCIENCE
(2020)
Article
Agricultural Engineering
Yuying Hu, Xiaohuan Zheng, Shihao Zhang, Wenjie Ye, Jing Wu, Souhila Poncin, Huai Z. Li
Summary: High solid anaerobic digestion (HSAD) is a potential organic waste treatment method with advantages of small footprint, less digestate, and low heating energy. Studying the hydrodynamics of HSAD showed that optimizing mixing can greatly increase its processing capacity.
BIORESOURCE TECHNOLOGY
(2021)
Article
Engineering, Chemical
Daofan Ma, Di Liang, Chunying Zhu, Taotao Fu, Youguang Ma, Xigang Yuan, Huai Z. Li
Summary: The study visually investigated the breakup process of viscous droplets in Y-shaped microchannels, highlighting the dynamics of droplet breakup with partial obstruction. The rupture process of droplets is divided into squeezing, transition, and rapid pinch-off stages, each displaying unique characteristics related to time, two-phase viscosity ratio, capillary number, and other factors. The findings provide insights into the factors influencing droplet breakup in microscale flow systems.
CHEMICAL ENGINEERING SCIENCE
(2021)
Article
Engineering, Environmental
Yuying Hu, Shihao Zhang, Xin Wang, Xiaoming Peng, Fengping Hu, Chuqiao Wang, Jing Wu, Souhila Poncin, Huai Z. Li
Summary: This study proposed a novel approach for experimentally quantifying the mass transfer in the mixing process of HSAD using the Laser Induced Fluorescence technique. The results showed that the feedstock tended to accumulate around the impeller in the HSAD system, and diffusion around the 1st impeller was rapid while around the 2nd impeller was tough. Prolonging mixing time did not significantly improve the flow pattern and mixing in HSAD.
Article
Engineering, Chemical
You Ma, Chunying Zhu, Taotao Fu, Youguang Ma, Huai Z. Li
Summary: The dynamics of non-Newtonian droplet breakup in a microfluidic Y-junction with partial obstruction was visually investigated. Three breakup stages were identified: squeezing, transition, and pinch-off. Factors such as the concentration of CMC, continuous capillary number, and dispersed phase local capillary number were found to affect the breakup process, with the pinch-off stage primarily determined by surface tension.
CHEMICAL ENGINEERING SCIENCE
(2021)
Article
Engineering, Chemical
Xiaofeng Jiang, Shixing Chen, Enle Xu, Xianliang Meng, Guoguang Wu, Huai Z. Li
Summary: This study investigates the downhill motion of liquid drops and liquid marbles using two distinct particle-laden interfaces. It is found that liquid marbles have a lower velocity than liquid drops but a higher maximum aspect ratio, indicating different interactions due to particles present on different surfaces.
Article
Agricultural Engineering
Fengping Hu, Shihao Zhang, Xin Wang, Chuqiao Wang, Jing Wu, Souhila Poncin, Li Xu, Gaoping Xu, Yuying Hu, Huai Z. Li
Summary: The study investigates the impact of impeller width on the correlation of mixing-fluidity-energy at different rotating speeds, as well as the scale-up effect based on rotating speed and a generalized Reynolds number. Results show that impeller widths of 100 mm (10 rpm), 200 mm, and 300 mm (5 and 10 rpm) are preferred for improving hydrodynamics and energy efficiency in HSAD. Additionally, the study suggests that Reynolds number similarity has significant implications for scale-up applications in practical engineering.
BIORESOURCE TECHNOLOGY
(2022)
Article
Chemistry, Multidisciplinary
Olfa Beji, Nouceiba Adouani, Souhila Poncin, Huai-Zhi Li
Summary: Biogas production from anaerobic digestion of different wastes is of growing interest in renewable energy. This study investigates the use of liquid digestate and slurry as substrates for microalgae-bacterial flocs growth and methane production. The results showed that 30% dilution of digestate and 10% dilution of slurry were optimal for nutrient removal and biomass production. The anaerobic digestion without flocs performed better in terms of methane production compared to digestion with flocs.
APPLIED SCIENCES-BASEL
(2022)
Article
Chemistry, Physical
Xiaofeng Jiang, Yi Zhou, Enle Xu, Xiangliang Meng, Guoguang Wu, Huai Z. Li
Summary: The impact of water drops on superhydrophobic surfaces (SHSs) with or without cavities was experimentally investigated in this study. Compared to plane SHSs, the cavity with different geometries reduces the maximum spreading diameter and contact time, and leads to complex drop deformation under higher We numbers. The dimensionless contact time on plane SHSs remains constant at about 0.88, while that on the cavity-textured SHSs is about 0.82. The drop impact on SHSs with macro-textured cavities exhibits different behaviors, which is important for applications such as self-cleaning and anti-icing.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2023)
Article
Chemistry, Multidisciplinary
Qindan Zhang, Souhila Poncin, Christian Blanchard, Youguang Ma, Huai Z. Li
Summary: The coalescence behavior of ferrofluid drop on its bulk surface was studied experimentally using a high-speed camera. Shape deformations of both the pendant ferrofluid drop and the bulk surface were observed in the axial direction during the approaching process, even without a magnetic field. The angle of the upper pendant peak decreases with increasing magnetic flux density, while the lower ferrofluid peak shows the opposite trend. The coalescing width of the ferrofluid drop follows a power-law relationship.
Article
Engineering, Chemical
Hao Jiang, Chunying Zhu, Taotao Fu, Xiqun Gao, Youguang Ma, Huai Z. Li
Summary: A new droplet sieving method using grooved microchannel is proposed for achieving droplet monodispersity. The sieving performance and mechanism are experimentally investigated, revealing three different sieving flow regimes: incomplete sieving, complete sieving, and main droplet rupture. The effects of different operating conditions on sieving efficiency are systematically studied.
SEPARATION AND PURIFICATION TECHNOLOGY
(2023)
Review
Engineering, Chemical
Dong Lin, Zhiwei Mao, Jingyuan Shang, Huihong Zhu, Tiebin Liu, Yining Wu, Huai Z. Li, Chong Peng, Xiang Feng
Summary: The second-generation biodiesel, generated through the deoxygenation of vegetable oils, is an ideal green fuel that can help address environmental pollution and the energy crisis. This review summarizes the catalyst design strategies, including the selection of metal active species, adjustment of coordination environment, and regulation of the metal-support interface, to provide insights into the catalytic mechanisms and guide the synthesis of catalysts for the deoxygenation of vegetable oils, promoting the industrialization process of second-generation biodiesel.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Biochemical Research Methods
C. Y. Tong, Huai Z. Z. Li, C. J. C. Derek
Summary: This study investigates cell detachment of Chlorella vulgaris from porous substrates in early cultivation stage using a microfluidic platform. Results show that increasing flow velocity enhances nutrient transport but also triggers cell detachment. The effect of flow velocity on cell detachment differs at different locations. These findings contribute to optimizing operating conditions and reactor design for algae cultivation systems.