Article
Mechanics
Devi Prasad Panigrahi, Pratyaksh Karan, Suman Chakraborty
Summary: The migration of a droplet under a thermal gradient is influenced by the variation of its interfacial tension with temperature. However, the traditional asymptotic analysis that considers only the variation of interfacial tension with the imposed thermal field may be fundamentally incorrect due to the coupling between the thermal field and the flow field through droplet deformation and thermal diffusion. Explicit interface tracking in three-dimensional space reveals that a linearly decreasing temperature profile enhances the droplet migration speed contrary to the prediction from asymptotic theory. This discrepancy is attributed to the alteration of the interfacial stress caused by the locally evolving temperature field.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Somnath Santra, Suman Chakraborty
Summary: The study demonstrates that controlling the axial oscillations can regulate the rate of transverse migration of droplets, and under the influence of an electric field, it is possible to achieve an increase in migration rate and reversal of lateral migration direction.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Ming-Kang Li, Shi-Ping Wang, Shuai Zhang, Hemant Sagar
Summary: This study experimentally investigates the complex interaction between underwater explosion (UNDEX) bubbles and a free surface. The dependence of the associated physics on the dimensionless detonation depth is revealed. Four typical bubble behavior patterns are identified and a critical value is found for ignoring the effects of the free surface on UNDEX bubbles. Good agreements are obtained with a unified theory for bubble dynamics. The dependence of pressure signals on the detonation depth is also investigated.
Article
Acoustics
Yongxing Song, Ruijie Hou, Zhengyang Liu, Jingting Liu, Weibin Zhang, Linhua Zhang
Summary: A novel rotorradial groove (RRG) hydrodynamic cavitation reactor with good cavitation intensity and energy utilization was proposed in this study. The research analyzed the cavitation performance of the RRG reactor and found that the rectangular-shaped CGU performed better than the cylindrical-shaped CGU. Increasing rotor speed and decreasing interaction distance could improve cavitation performance more effectively.
ULTRASONICS SONOCHEMISTRY
(2022)
Article
Mechanics
Nalinikanta Behera, Antarip Poddar, Suman Chakraborty
Summary: We report the migration of eccentric compound drops under a uniform electric field and the additional effects induced by dielectrophoretic forces. The relative velocity between the inner and outer drops dictates the evolution of eccentricity variation, resulting in four distinct migration regimes based on electro-physical properties. The increase in eccentricity and size ratio of droplets can induce monotonic or non-monotonic variation in drop velocities, providing control over selectively increasing or suppressing eccentricity over time.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Chemistry, Physical
Wenjie Ji, Ding Lan, Weibin Li, Quanzi Yuan, Yuren Wang
Summary: This article proposes a wall-confined spreading dynamics (WCSD) model based on molecular kinetic theory (MKT), which creatively illustrates the relationship between driving energy and energy dissipation using a phase diagram. It reveals the mechanical mechanism of liquid spreading over another and provides guidance for the growth of two-dimensional molecular crystals (2DMCs) solution processing methods.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Mechanics
J. L. Liu, W. Xiao, X. L. Yao, X. H. Huang
Summary: The dynamics of a bubble in a liquid fully confined by an elastic boundary were investigated using a numerical model based on the boundary element method. The results showed that the confinement led to rapid oscillation of the bubble and generation of a jet along the eccentric direction. Factors such as elastic modulus of the boundary, size of the confinement, and eccentric position of the bubble influenced the bubble oscillation, with higher elastic modulus and smaller confinement size leading to decreased amplitude and cycle of oscillation.
Article
Chemistry, Physical
Panlin Jin, Kexin Zhao, Zoe Blin, Malou Allais, Timothee Mouterde, David Quere
Summary: The spectacular nature of non-wetting drops is due to their extreme mobility, as exemplified by quicksilver. Two methods to achieve non-wetting involve utilizing texture: roughening a hydrophobic solid to create pearl-like drops, or texturing the liquid with a hydrophobic powder to isolate the resulting marble from its substrate. In this study, we observe and report two effects: the static adhesion of pearls and marbles differs in nature, potentially due to their interaction with the substrate; when in motion, pearls are generally faster than marbles, possibly due to differences in the liquid/air interface between these two types of droplets.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Mechanics
Yuan Si Tian, Zi Qiang Yang, Sigurdur T. Thoroddsen
Summary: Fast microjets can be produced when drop-impact craters rebound or when a bubble bursts, and they play a crucial role in climate and olfactory senses as a source of aerosols. The most unique and fastest jets are generated when a small dimple forms at the crater bottom and rebounds without pinching off a small bubble. High-resolution numerical simulations reveal a new focusing mechanism that explains the extreme sensitivity to initial conditions observed in experiments of this phenomenon.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Sreeparna Majee, Abhishek Saha, Saptarshi Basu
Summary: This study presents a numerical investigation of the transport and evaporation dynamics of an isolated droplet in an oscillating gas-phase flow. The results show that increasing the amplitude or frequency of the gas-phase oscillation accelerates the evaporation process, and the unsteadiness of the external flow also affects the liquid-phase transport inside the droplet. A scaling analysis is conducted to unify the observed evaporation dynamics and predict the effects on the evaporation rate.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Durbar Roy, M. Sophia, Saptarshi Basu
Summary: We studied the impact of drops on an immiscible viscous liquid pool and investigated the formation of surface craters using experimental and theoretical analyses. The formation of air craters was attributed to the rapid deceleration of the droplets due to viscous drag force. We introduced a non-dimensional parameter (gamma) to analyze the relationship between the drag force and the capillary force acting on the droplets. We also developed local and global response models to explain the droplet deformation profiles.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Shubham Sharma, Awanish Pratap Singh, S. Srinivas Rao, Aloke Kumar, Saptarshi Basu
Summary: The multiscale dynamics of shock-droplet interaction is crucial for understanding droplet atomisation due to external airflow. The interaction phenomena are classified into wave dynamics and droplet breakup dynamics, primarily observing different breakup modes for the studied range of Weber numbers.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Shubham Sharma, Awanish Pratap Singh, Saptarshi Basu
Summary: This study elucidates the mechanism of co-axial interaction between droplets and vortex rings of different circulation strengths. Experimental and theoretical analyses of droplet and vortex dynamics show that the interaction leads to a reduction in circulation strength, total energy and enstrophy.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Navin Kumar Chandra, Shubham Sharma, Saptarshi Basu, Aloke Kumar
Summary: This study investigates the aerobreakup of non-Newtonian droplets under the influence of airflow. Polymeric droplets of different concentrations were subjected to induced airflow behind a moving shock wave to explore the role of elasticity in modulating the aerobreakup of viscoelastic droplets. Three distinct modes of aerobreakup were identified, namely vibrational, shear-induced entrainment, and catastrophic breakup, for a wide range of Weber number and elasticity number variation. Each mode is described as a three-stage process, including droplet deformation, appearance and growth of hydrodynamic instabilities, and evolution of liquid mass morphology. The results suggest that elasticity plays a dominant role in the final stage of the aerobreakup process.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Physics, Fluids & Plasmas
Elijah D. Andrews, Ivo R. Peters
Summary: In this study, an inexpensive numerical model based on the boundary element method was developed to predict the anisotropy parameter of gas or vapor bubbles in complex rigid geometries. Experimental results showed that bubble displacement in a range of complex geometries behaves as a function of the predicted anisotropy parameter values.
PHYSICAL REVIEW FLUIDS
(2022)
