Article
Mechanics
Qiang Ma, Yi-Feng Wang, Yi-Bo Wang, Xin He, Shao-Fei Zheng, Yan-Ru Yang, Xiao-Dong Wang, Duu-Jong Lee
Summary: The impact dynamics of water nanodroplets on flat solid surfaces were studied using molecular dynamics simulations, identifying eight different impact outcomes and classifying them into non-bouncing, bouncing, and splash. The splash phenomenon is triggered only when the Weber number exceeds 140.
Article
Chemistry, Multidisciplinary
Xin He, Yi-Feng Wang, Ben-Xi Zhang, Shuo-Lin Wang, Yan-Ru Yang, Xiao-Dong Wang, Duu-Jong Lee
Summary: The study investigates wetting and dewetting behaviors of water nanodroplets on nanopillar-arrayed surfaces with or without an electric field through MD simulations. Results show that the presence of an electric field affects the energy barriers separating Cassie and Wenzel states for nanodroplets. The Cassie state becomes more robust with increased energy barrier, and a critical water molecule number determines the stability of Wenzel configurations.
Article
Chemistry, Physical
Qiang Ma, Yi-Feng Wang, Yi-Bo Wang, Ben-Xi Zhang, Shao-Fei Zheng, Yan-Ru Yang, Duu-Jong Lee, Xiao-Dong Wang
Summary: The bouncing dynamics of water nanodroplets on superhydrophobic Pt surfaces with nanopillar arrays is comprehensively studied using molecular dynamics simulations. It is found that there are critical values of the solid fraction and pillar height to induce pancake bouncing at the moderate Weber number. A theoretical model is developed to quantitatively proclaim the dependence of nanostructure features and the critical Weber number on pancake bouncing.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Physical
Aiping Zhang, Kai Cui, Yuanyuan Tian, Tieying Wang, Xin He
Summary: This article investigates the impact behavior of binary nanodroplets on hydrophobic and superhydrophobic surfaces, using molecular dynamics simulations to directly capture and analyze the dynamic evolutions of droplets. It provides insights into the practical applications of droplet impact and contributes to advancements in this field.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Mechanics
Ben-Xi Zhang, Jiang-Hai Xu, Kai-Qi Zhu, Yan-Yi Zhang, Yan-Ru Yang, Xiao-Dong Wang
Summary: The statics and dynamics of spreading-evaporating nanodroplets under parallel electric fields and free evaporation conditions were investigated through molecular dynamics simulations. The results showed that at a substrate temperature of 320 K, the contact angles on the left and right edges were initially asymmetric and then became symmetric with increasing field strengths, leading to the asymmetric-to-symmetric spreading transition. Under weak evaporation conditions, the asymmetric-to-symmetric spreading transition was triggered by increasing surface wettability at a constant field strength. However, at a substrate temperature of 350 K, the symmetric-to-asymmetric spreading transition appeared first, followed by the asymmetric-to-symmetric transition with increasing field strength. Under strong evaporation conditions, the asymmetric-to-symmetric spreading transition also occurred with increasing surface wettability at a constant field strength.
Article
Chemistry, Physical
Xin He, Kai Cui, Wei Hai Dong, Xing Juan Zhang, Ze Feng Zhou, Shuo Lin Wang
Summary: This work focuses on using super-hydrophobic surfaces with stepped textures to passively manipulate the impact dynamics of nanodroplets. The study reveals novel impact dynamics, such as deflected rebound and splitting of droplets, which are different from normal impacts on smooth surfaces. The asymmetric dynamics of impacting droplets on stepped surfaces are found to be the primary reason for these observed phenomena. This research provides insights into manipulating droplets at the nanoscale and can benefit practical applications.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2023)
Article
Nanoscience & Nanotechnology
Yifeng Ni, Qj Tong
Summary: Through molecular dynamics simulations, this study reveals the dynamic behaviors of a mixture of water droplets and particles at the nanoscale on a specific surface. Three different styles of motion, including sweeping, separating, and pinning, are observed as the interaction strengths among the substances vary. The results provide insights into the fundamental understanding of dynamic behaviors at the nanoscale and may have potential applications in areas such as drug delivery, dust cleaning of nanomachines, and liquid purification.
ACS APPLIED NANO MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
Run Liu, Yan-Ru Yang, Xiao-Dong Wang
Summary: This study investigates nanodroplet splitting induced by electrowetting-on-dielectric between two parallel plates using molecular dynamics simulations, showing that the splitting dynamics depend on the charge density applied to electrodes and the critical charge density is influenced by plate gap and electrode size. A new criterion based on the geometric relations between droplets and electrode sizes is proposed to predict whether nanodroplets can be split, which is in agreement with MD simulations.
MICROFLUIDICS AND NANOFLUIDICS
(2021)
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, Physical
Xiong Wang, Xiao Yan, Jiayu Du, Bingqiang Ji, Mohammad Jalal Inanlu, Qi Min, Nenad Miljkovic
Summary: The spreading behavior of microdroplets differs from larger droplets due to the influence of size and surface tension. Experiments showed that the initial spreading of smaller droplets is shorter with reduced oscillation damping compared to millimeter-scale droplets. The coupling between spreading velocity and dynamic contact angle may have applications in microscale heat transfer, advanced manufacturing, and aerosol transmission studies.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Chemistry, Physical
Shuhang Lyu, Zhen Yang, Yuanyuan Duan
Summary: In this study, the dissipative force and sliding mode of moving nanodroplets on hydrophobic surfaces were investigated using molecular dynamics simulation. The results showed that the dissipative force had a significant effect on nanodroplets and they exhibited a combination of rolling and slipping motion on the surfaces. The effects of striped structure on the dissipative force and sliding mode were also studied.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Chemistry, Physical
Jiayu Du, Yiyang Zhang, Qi Min
Summary: This study investigated the spreading and retraction dynamics of viscous droplets impact on flat solid surfaces using an efficient continuum-level modeling method. The study analyzed the influence of droplet viscosity, impact velocity, and material wettability on the dynamic characteristics of droplets, and developed multiple general correlations to predict various factors. It was successfully proven that this modeling method can be reliably applied to investigations of both droplet spreading and retraction processes.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2021)
Article
Chemistry, Physical
V. Arun Kumar, V. Sajith, Sarith P. Sathian
Summary: Experimental and molecular dynamic simulations were used to study the evaporative behavior of liquid droplets in the presence of nanoparticles. It was found that droplets with higher density nanoparticles exhibit pinned behavior and promote pattern formation during evaporation. The simulations also suggest that higher nanoparticle-liquid interaction strengths lead to a delay in evaporation while experiencing higher heat flux on the substrate.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2021)
Article
Chemistry, Physical
Robin Koester, Michael Vogel
Summary: In this study, molecular dynamics simulations were conducted to investigate the confinement effects of ionic liquids between amorphous silica surfaces. The results showed a significant slowdown of ion dynamics near the surfaces. The analysis revealed a broad distribution of residence times for anions at adsorption sites, following Arrhenius laws. Additionally, the amorphous silica surfaces imposed static and disordered energy landscapes, hindering ion rearrangements.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Thermodynamics
Ben-Xi Zhang, Shuo-Lin Wang, Yi-Bo Wang, Shu-Rong Gao, Yan-Ru Yang, Xiao-Dong Wang
Summary: The spreading of nanodroplets on heated nanostructured surfaces is influenced by scale effects, with noticeable differences in early spreading stages compared to larger droplets. While initial spreading on nanostructured surfaces is hindered by a pinning effect due to the comparable sizes of nanodroplets and surface features, more significant evaporation in later stages leads to a reduction in the difference in spreading radius between smooth and nanostructured surfaces. Surface temperature, wettability, and aspect ratio of the nanostructures all play roles in impacting the spreading behavior of nanodroplets, with evaporation rates showing abnormal patterns on surfaces with moderate wettability.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
