Article
Physics, Fluids & Plasmas
Thijs de Goede, Karla de Bruin, Noushine Shahidzadeh, Daniel Bonn
Summary: This paper investigates the influence of surface roughness on droplet splashing, showing that rough surfaces can change the splashing velocity of droplets. When the droplet roughness is large enough, it changes the droplet splashing mechanism from corona to prompt splashing. The study also demonstrates that the measured splashing velocity for water and ethanol on surfaces with different roughnesses can be collapsed onto a single curve, indicating that the droplet splashing velocity on rough surfaces scales with the Ohnesorge number defined with the surface roughness length scale.
PHYSICAL REVIEW FLUIDS
(2021)
Article
Thermodynamics
Pouya Sharbati, Abdolali K. Sadaghiani, Ali Kosar
Summary: This study investigates the influence of contact angle (CA) and contact angle hysteresis (CAH) on humid air condensation and reveals their different roles in different stages of the condensation cycle. The findings show that increasing CAH has a negative effect on condensation heat transfer, while the impact of changing CA varies. Lower CAH values have a greater impact on enhancing condensation heat transfer, and increasing CAH has a more significant effect on hydrophobic surfaces than on hydrophilic surfaces. Additionally, decreasing CAH has a more pronounced effect on improving condensation heat transfer than increasing CA.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Chemistry, Physical
Abrar Ahmed, Raymond Sanedrin, Thomas Willers, Prashant R. Waghmare
Summary: The study suggests that drop deposition techniques can impact contact angle measurements, mainly due to drop pinch-off and dynamic wetting pressure. Experimental comparison of parameters in pendant drop and liquid-needle techniques reveals a pronounced drop volume dependency for the former but not the latter. This highlights the importance of well-controlled drop deposition to ensure accurate contact angle data independent of deposition effects.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2022)
Article
Energy & Fuels
Yumeng Chen, Baonan Zhou, Xurui Zhang, Siyuan Yang, Wei Huang
Summary: Kerosene can enhance the hydrophobicity of coal and the bubble attachment capacity, showing more pronounced outcomes when present on both surfaces. At a microscopic scale, kerosene promotes the kinetics of film thinning, but does not cause film rupture due to attractive disjoining pressure.
Article
Thermodynamics
Joo Hyun Moon, Sangmin Lee, Chang Kyoung Choi, Seong Hyuk Lee
Summary: This study experimentally investigated the dynamic characteristics of a liquid droplet on microscale hole-patterned surfaces, comparing the effects of anodization on hydrophilicity. Results showed that the dynamic contact angle decreased with an increase in hole area fraction for the anodized surfaces, while the equilibrium and dynamic contact angles increased for non-anodized surfaces. Additionally, the dynamic contact diameter increased with area fraction and Weber number for anodized surfaces.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
Article
Chemistry, Multidisciplinary
Stephan B. Lunowa, Arjen Mascini, Carina Bringedal, Tom Bultreys, Veerle Cnudde, Iuliu Sorin Pop
Summary: This study investigated the mathematical models for capillary-driven flow of fluids in tubes and found that the dynamic contact angle and inertial effects have significant impacts on the model predictions. The newly developed models can accurately match experimental data and are sensitive to the properties of the fluid rather than the geometrical features.
Article
Thermodynamics
B. B. Kazemian, P. Cheng
Summary: A variable solid-fluid interaction strength scheme compatible with the lattice Boltzmann method is introduced to investigate contact angle hysteresis phenomena numerically. The method is demonstrated to accurately reproduce the observed behaviors during droplet sliding and evaporation processes, and the results are in agreement with previous experimental investigations.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Pharmacology & Pharmacy
Qing Zhang, Xiaoling Li, Bhaskara R. Jasti
Summary: This study investigated the relationships between physicochemical properties of HPMC compacts and their in vitro mucoadhesive performances. It found positive correlations between viscosity, contact angle, hydration, and mucoadhesive force of HPMC compacts. The polar lipid content in mucosa was identified as an important factor affecting mucoadhesion, and thermodynamic analysis provided insights into the mucoadhesive mechanism of different grades of HPMC compacts.
INTERNATIONAL JOURNAL OF PHARMACEUTICS
(2021)
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)
Article
Engineering, Marine
Ning Gan, Xiongliang Yao, Biao Su, Xiongwei Cui
Summary: This paper investigates the behavior of a ventilated bubble injected from a vertical flat surface into a cross-flow. Numerical simulations using OpenFOAM are carried out to study the effects of contact angle, incoming flow direction relative to gravity, and surface tension on the dynamic behavior of the ventilation bubble. The results show that there is a critical contact angle of 90 degrees, beyond which the development of the ventilation bubble along the cross-section is significantly enhanced. Different gas leakage modes are observed at the rear of the bubble, including spherical bubbles falling off and local gas leaks in the form of elongated bubbles. Additionally, when the surface tension coefficient is less than 0.036 N/m, the morphology of the bubble undergoes a significant change, and the bubble develops faster along the width direction. The effect of surface tension induced by changes in fluid characteristics on bubble development is similar to that induced by different wall types.
Article
Chemistry, Physical
Xiong Wang, Xiao Yan, Jiayu Du, Feipeng Chen, Fanfei Yu, Ran Tao, Steven Wang, Qi Min
Summary: This study experimentally investigated the wetting differences between Newtonian and viscoelastic fluids on microstructured surfaces. The results showed that the relationship between the dynamic contact angle and moving velocity differed for different microstructured surfaces for these fluids. The differences were influenced by variations in viscosity and elasticity, while the scale of microstructured surfaces had little effect.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Gaia Kravanja, Inna A. Belyaeva, Luka Hribar, Irena Drevensek-Olenik, Matija Jezersek, Mikhail Shamonin
Summary: The study reveals a significant effect of an external dc magnetic field on the splashing behavior of ethanol drops impacting on the surface of soft magnetoactive elastomers, including a reduced transition Weber number and an increased initial deceleration of the ejection sheet. The main mechanism observed is believed to be the magnetic-field-induced stiffening of the magnetoactive elastomers.
ADVANCED MATERIALS INTERFACES
(2021)
Article
Mechanics
Binjian Ma, Dafeng Li, Huizhu Yang
Summary: Capillary rise is a common phenomenon in engineering applications and natural phenomena. While the dynamics of capillary rise in straight channels are well understood, the dynamics in nonuniform channels of varying radius remain largely unclear. This study investigates the capillary rise in a sinusoidal wavy channel both analytically and numerically, and reveals the significant influence of interfacial effects on the capillary velocity and height.
Article
Polymer Science
Masayuki Saito, Kohzo Ito, Hideaki Yokoyama
Summary: This article describes a method for analyzing the interfacial energy of a dynamic polymer brush interface and validates the existence of negative interfacial energy through the calculation of free energy balance.
Article
Chemistry, Physical
Dohyung Kim, Minki Lee, Jeong-Hyun Kim, Jinkee Lee
Summary: The study found that the dynamic contact angles on LIS are sensitive to changes in both the lubricant viscosity and the capillary number, and the cube of the dynamic contact angles is proportional to theta(3)(D), following a conventional hydrodynamic theory. The decreasing lubricant viscosity shifted the cube of the dynamic contact angles to high capillary numbers, and the dynamic contact angle data coincided with the prediction from a scaling law derived in this study.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2021)
Article
Mechanics
Qijie Li, Kensuke Yokoi, Zhihua Xie, Syazana Omar, Jingjing Xue
Summary: A new modified WENO strategy and THINC scheme are proposed in this study to improve numerical dissipation and better represent discontinuity, with numerical verifications showing that the proposed schemes achieve high-resolution quality in capturing both smooth and discontinuous flow structures simultaneously.
Article
Thermodynamics
Fabian Denner, Fabien Evrard, Alfonso Arturo Castrejon-Pita, Jose Rafael Castrejon-Pita, Berend van Wachem
Summary: This study analyses the capillary breakup of a liquid jet under large excitation amplitudes relevant to inkjet printing using numerical simulations. The results show the reversal of breakup length and inversion of breakup modes, both related to the formation of vortex rings and local flow obstruction inside the jet. An empirical similarity model for the breakup length reversal is proposed, allowing accurate prediction of jet behavior in practical situations, especially continuous inkjet printing.
FLOW TURBULENCE AND COMBUSTION
(2022)
Article
Mechanics
Karrar H. Al-Dirawi, Khaled H. A. Al-Ghaithi, Thomas C. Sykes, J. Rafael Castrejon-Pita, Andrew E. Bayly
Summary: Binary droplet collisions can result in coalescence or stretching separation, with the transition between these outcomes dependent on high Weber numbers and impact parameters. The effect of viscosity on this transition is revealed in an experimental study, showing an inertial behavior over a wide range of Ohnesorge numbers. Compelling evidence is provided to show that stretching separation only occurs when the length of the coalesced droplet exceeds a critical multiple of the original droplet diameters.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Qijie Li, Junqiang Xia, Kensuke Yokoi, Syazana Omar
Summary: This study introduces a new constrained interpolation profile conservative semi-Lagrangian method based on a novel boundary variation diminishing algorithm, which effectively reduces numerical dissipation near critical regions. By utilizing two candidate schemes, it successfully optimizes interface capturing and reconstruction of smooth solutions to eliminate numerical oscillation and diffusion, showing potential for application in a wide range of engineering problems.
Article
Multidisciplinary Sciences
M. A. Quetzeri-Santiago, J. R. Castrejon-Pita, A. A. Castrejon-Pita
Summary: Dielectrowetting can actively control the dynamics of droplet impact to prevent bouncing and suppress splashing. The strength of the electric potential can regulate the dynamic contact angle and affect the spreading, splashing, and receding dynamics.
SCIENTIFIC REPORTS
(2021)
Article
Chemistry, Physical
Thomas C. Sykes, Ben D. Fudge, Miguel A. Quetzeri-Santiago, J. Rafael Castrejon-Pita, Alfonso A. Castrejon-Pita
Summary: This study investigates the splashing behavior of millimetric droplets on convex and concave surfaces, and finds that the tendency of droplets to splash is proportional to the reciprocal of the substrate's radius of curvature, with it being harder for droplets to splash on small spheres.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2022)
Article
Mechanics
C. R. Constante-Amores, J. Chergui, S. Shin, D. Juric, J. R. Castrejon-Pita, A. A. Castrejon-Pita
Summary: In this study, the effect of insoluble surfactants on the retracting dynamics of thin water sheets is investigated using an interface-tracking/level-set method. It is found that the surfactant concentration can delay or prevent the breakup of the sheet edge, revealing the significant role of Marangoni stresses in the retracting dynamics.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Kensuke Yokoi
Summary: This paper proposes a novel third-order compact stencil-based upwind scheme for the approximation of the continuity equation, which has lower oscillation and diffusion. The scheme exhibits high accuracy in numerical results and is able to capture both smooth solutions and discontinuities simultaneously, demonstrating excellent applicability.
Article
Chemistry, Physical
Miguel A. Quetzeri-Santiago, David Fernandez Rivas
Summary: The study investigates the impact of microfluidic jets on a capillary bridge and compares the cavity formation and collapse between different materials. The effects of wettability on adhesion forces and contact line dissipation are also studied.
Article
Chemistry, Physical
Diana L. van der Ven, Davide Morrone, Miguel A. Quetzeri-Santiago, David Fernandez Rivas
Summary: Exploring the relation between microfluidic jet characteristics and substrate shear modulus helps predict and gain insights on the impact outcome. Seven impact regimes were found, and three thresholds were identified. Jet velocity has a higher predictive value for injection depth compared to the Weber-number or jet diameter.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Mechanics
C. R. Constante-Amores, L. Kahouadji, S. Shin, J. Chergui, D. Juric, J. R. Castrejon-Pita, O. K. Matar, A. A. Castrejon-Pita
Summary: We investigate the influence of insoluble surfactants on the impact of surfactant-free droplets onto surfactant-laden thin liquid films using a three-dimensional numerical simulation approach. Our results show that the presence of surfactants affects the late stages of the dynamics by delaying the end-pinching mechanisms, resulting in longer ligaments. We also demonstrate that the addition of surfactants leads to surface rigidification and retards the flow dynamics.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Jelle J. J. Schoppink, Keerthana Mohan, Miguel A. A. Quetzeri-Santiago, Gareth McKinley, David Fernandez Rivas, Andrew K. K. Dickerson
Summary: By selectively coating hydrophobic strips on hydrophilic glass capillaries, the trajectory and characteristics of the microjet can be influenced and controlled.
Article
Mechanics
Thomas C. Sykes, Radu Cimpeanu, Ben D. Fudge, J. Rafael Castrejon-Pita, Alfonso A. Castrejon-Pita
Summary: When a fast droplet impacts a pool of the same fluid, the depth of the pool is revealed to be a critical factor in the formation of ejecta sheets. On deeper pools, the sheets fold inwards, while on shallower pools, they develop into outward-propagating lamellae. This transition is caused by a confinement effect of the pool base on the impact-induced pressure, which restricts flow into the ejecta sheet from the droplet.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
K. L. Meza-Alarcon, M. A. Quetzeri-Santiago, M. A. Neri-Flores, J. Antonio del Rio, J. R. Castrejon-Pita
Summary: In this study, the behavior and spreading dynamics of molten metallic alloy droplets were investigated. The impact behavior of five different solders was analyzed in terms of material and impact conditions. The results showed that the impact behavior could be well described by the splashing ratio and the maximum dynamic spreading contact angle. This study provides useful criteria for selecting the soldering injection speed and droplet size in industrial applications to prevent splashing during soldering or molten metal jetting.
