Article
Mechanics
David Baumgartner, Guenter Brenn, Carole Planchette
Summary: A model is developed to predict the fragmentation limit of drops colliding off-centre, which is excellent over a wide range of liquid properties. The stretching separation is attributed to the extension of the merged drop above a critical aspect ratio influenced by liquid viscosity. The model is then adapted to drop-jet collisions, with similar fragmentation criteria but modified aspect ratio evolution to account for different flow fields and geometry.
JOURNAL OF FLUID MECHANICS
(2022)
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
Physics, Fluids & Plasmas
A. Rubio, F. J. Galindo-Rosales, E. J. Vega, J. M. Montanero, M. G. Cabezas
Summary: This paper investigates the viscoelastic transition in transonic flow focusing when polymers of low molecular weights are dissolved in water at the appropriate concentration. The phenomenon is explained through the coil-stretch transition of polymers crossing the tapering meniscus, where high strain rates are produced by the airstream. The resulting elastic stress stabilizes the flow, leading to thinner and longer jets compared to Newtonian fluids, which has important implications at the technological level.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Mechanics
Hui Zhao, Dung Nguyen, Daniel Edgington-Mitchell, Julio Soria, Hai-Feng Liu, Damon Honnery
Summary: This study aims to investigate the largest diameter of falling drop in the up-gas flow. The phenomenon of drop breakup in the airflow, known as secondary atomization, is commonly observed in nature and industry. The critical Weber number is used to determine the beginning of drop breakup. This study explains the different critical Weber numbers for free-fall raindrops breakup and secondary atomization based on the Rayleigh-Taylor instability. The study proposes a theoretical criterion for the largest raindrop size and suggests a map of falling drop size regions to explain the occurrence of super-large raindrops. Additionally, the findings of this study have practical implications for reducing drop entrainment in washing towers.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2023)
Article
Multidisciplinary Sciences
Lingzhi Cai, Joel Marthelot, P-T Brun
Summary: The breakup of liquid threads into droplets is a common phenomenon in engineering and natural environments. Previous studies have mainly focused on axisymmetric systems, while the physics of multiple threads and the interaction between threads and symmetry-breaking boundaries have not been explored. This study discovered that closely spaced liquid threads printed in an immiscible bath form crystal-like lattices of droplets. By controlling the injection flow rate and nozzle translation speed, the lattice pattern can be adjusted, overcoming the limitations of structural versatility in existing fluid manipulation paradigms. Furthermore, it was found that these drop crystals have the ability to self-correct.
Article
Mechanics
Lei Zheng, Rui Zhao, Yong-Le Nian, Jun Liu, Wen-Long Cheng
Summary: This paper investigates the influence of nozzle's tangential velocity to axial velocity ratio and swirl diversion channel eccentric distance on spray parameters. Results show that both parameters have a linear relationship with the peak location of each spray parameter.
Article
Engineering, Mechanical
Guillaume Maitrejean, Denis C. D. Roux, Maxime Rosello, Pascal Jay, Jean Xing, Bruno Barbet
Summary: A mixed experimental-numerical strategy is used to assess the relaxation time measurement of a weakly elastic polymer solution. The relaxation time is determined by comparing the jetting of the polymer solution experimentally and numerically, using a validated numerical approach and a viscoelastic Oldroyd-B model.
JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME
(2022)
Article
Crystallography
Alfonso M. Ganan-Calvo, Henry N. Chapman, Michael Heymann, Max O. Wiedorn, Juraj Knoska, Braulio Ganan-Riesco, Jose M. Lopez-Herrera, Francisco Cruz-Mazo, Miguel A. Herrada, Jose M. Montanero, Sasa Bajt
Summary: The successful introduction of samples in Serial Femtosecond Crystallography has been achieved by using microscopic capillary liquid jets produced by gas flow focusing. A classical scaling law with two universal constants has been validated to accurately calculate the length of the liquid jets based on experimental and numerical measurements. The actual length of the jet is determined by nonlinear perturbations from the jet breakup itself, in contrast to the classical conception of temporal stability attributing natural breakup length to jet birth conditions or small interactions with the environment.
Article
Nanoscience & Nanotechnology
Liang Hu, Lei She, Yanshen Fang, Rui Su, Xin Fu
Summary: This article investigates the effects of driving and jet parameters on the deformation characteristics of droplets generated by Rayleigh jet breakup. Numerical solutions simulate spatial instability of jet breakup and non-linear jet breakup influences droplet oscillation amplitude.
Article
Mechanics
Mengsen Zhang, Jianqin Zhu, Zhi Tao, Lu Qiu
Summary: The experimental study investigated the breakup characteristics of micro rectangular jets with external disturbances. The evolution of the ejected rectangular jet was observed to go through three stages, leading to the formation of a structured droplet train. Factors influencing the formation of droplet train were identified, such as jet velocity and disturbance frequency.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2021)
Article
Mechanics
Shirin Patil, Srikrishna Sahu
Summary: The paper reports on spray characterization in a novel twin-jet airblast injector, focusing on the effect of injector air swirl on droplet characteristics and dispersion behavior. The addition of air swirl significantly affects spray topology and droplet size downstream of the injector exit, leading to improved atomization quality and high spray dispersion. The results provide insight into the physics behind the improved atomization due to air swirl and demonstrate the injector's ability to achieve atomization quality and high spray dispersion over a wide operating range.
Article
Thermodynamics
Jun Zhang, Pengfei Liang, Youzhi Liu
Summary: In this study, a free opposed impinging jets with unequal nozzle diameter was developed to enhance mixing efficiency for liquid-liquid reactions at unequal flowrates. The characteristics of liquid sheet breakup and droplet behavior were investigated using particle image velocimetry. The experimental results showed that the breakup mode of the liquid sheet transitioned from closed-rim mode to open-rim mode, rimless mode, wave or ligament mode, and fully developed mode as the jet velocity increased. The increase in jet velocity resulted in a decrease in sheet thickness, Sauter mean diameter, average droplet diameter, and droplet velocity, as well as a more uniform droplet size.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2023)
Article
Mechanics
M. Rubio, A. Ponce-Torres, M. A. Herrada, A. M. Ganan-Calvo, J. M. Montanero
Summary: This study investigates experimentally and numerically the thinning process of Newtonian leaky-dielectric filaments under an axial electric field, as well as the influence of the electric field on the formation of satellite droplets. The electric force delays surface pinching, with polarization stress being identified as a key factor in this delay. Additionally, near the pinching point, hydrodynamic forces dominate filament thinning while the polarization stress becomes subdominant despite its divergence at the finite-time singularity.
Article
Mechanics
Rina Nakajima, Kosuke Hayashi
Summary: Experiments were conducted to study the behavior of liquid drops falling through a miscible liquid. It was observed that the drops deform into vortex rings and fragment into smaller drops due to the Rayleigh-Taylor instability. The number of smaller drops was measured for different Archimedes numbers, and the influence of vortex ring interactions on fragmentation was analyzed.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2022)
Article
Mechanics
Sharey Deep Guleria, Atul Dhar, Dhiraj V. Patil
Summary: This article presents experimental insights into the physics of water entry of hydrophobic spheres. Various parameters and dynamics of the trapped air-cavity are studied, including cavity formation, retraction, and Worthington-jet analysis. Different cavity shapes exhibit unique radial dynamics and surface energy characteristics, with specific behaviors such as bubble shedding observed for shallow seal conditions.
Review
Acoustics
Tim Boers, Sicco J. J. Braak, Nicole E. T. Rikken, Michel Versluis, Srirang Manohar
Summary: Ultrasound, the primary imaging modality in thyroid nodule management, has limitations such as variability, limited field-of-view and functional imaging. However, current developments in ultrasound technologies, such as three-dimensional-Doppler, -elastography, -nodule characteristics-extraction, and machine-learning algorithms, are aimed at overcoming these limitations. The use of three-dimensional ultrasound in thyroid ablative treatments and biopsies is a promising area of research. This review provides an overview of the current and future applications of ultrasound in thyroid nodule management and discusses the potential of new developments and trends to improve diagnosis, therapy, and follow-up.
JOURNAL OF CLINICAL ULTRASOUND
(2023)
Article
Mechanics
Mogeng Li, Detlef Lohse, Sander G. Huisman
Summary: We experimentally investigated the evaporation of highly volatile liquid droplets (Novec 7000 Engineered Fluid, HFE-7000) in a turbulent spray. The droplets were produced by a spray nozzle and injected into a purpose-built chamber filled with air containing varying amounts of water vapor. The results showed that water condensation occurred on the rapidly evaporating droplets, and a more humid environment led to faster evaporation and more water condensation. An analytical model based on Fick's law was used to quantitatively explain the data.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Multidisciplinary Sciences
Luuk J. Blaauw, Detlef Lohse, Sander G. Huisman
Summary: Using the Taylor-Couette geometry, we studied the impact of salt on drag reduction caused by bubbles in the flow. The drag reduction was found to decrease as the salt concentration increased, from 40% in fresh water to 15% in sea water. The presence of salts inhibited coalescence events, resulting in smaller bubbles and decreased drag reduction.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2023)
Article
Physics, Fluids & Plasmas
Christopher J. Howland, Roberto Verzicco, Detlef Lohse
Summary: Motivated by ice ablation in salt water, this study investigates the heat and salt fluxes in two-scalar vertical convection using three-dimensional direct numerical simulations. The salinity field drives the convection while heat is transported as passive scalar. The diffusivity ratio of heat and salt affects the scalar fluxes, with heat transport determined by a turbulent Prandtl number of Prt approximate to 1 and double-diffusive effects being negligible.
PHYSICAL REVIEW FLUIDS
(2023)
Article
Computer Science, Interdisciplinary Applications
Youssef Saade, Detlef Lohse, Daniel Fuster
Summary: We extend the all-Mach solver proposed by Fuster and Popinet (2018) [1] to account for heat diffusion between two compressible phases. By solving a coupled system of equations for pressure and temperature, our code improves the robustness and accuracy of the solver compared to classical explicit discretization schemes. Several test cases are used to validate the implementation, including comparisons with spectral methods and analytical solutions. The code is also applied to the study of sonoluminescent bubbles, Rayleigh collapse, and bubble collapse near a rigid boundary, demonstrating the importance of thermal effects in these phenomena.
JOURNAL OF COMPUTATIONAL PHYSICS
(2023)
Article
Multidisciplinary Sciences
Georges Chabouh, Benjamin van Elburg, Michel Versluis, Tim Segers, Catherine Quilliet, Gwennou Coupier
Summary: This study analyzes the buckling events of elastic shells through quasi-static compression experiments on lipidic shells and compares them with acoustic characterization results, deducing the mechanical characteristics of these shells.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2023)
Article
Physics, Applied
Maaike Rump, Uddalok Sen, Roger Jeurissen, Hans Reinten, Michel Versluis, Detlef Lohse, Christian Diddens, Tim Segers
Summary: In practical applications of inkjet printing, the intermittent idle periods of printhead nozzles lead to evaporation of ink from the nozzle exit. This evaporation results in concentration gradients within the multicomponent inks, which can directly and indirectly affect the jetting process, reproducibility, and print quality. This study investigates selective evaporation of water-glycerol mixtures from an inkjet nozzle through experiments, analytical modeling, and numerical simulations. The research sheds light on the complex physiochemical hydrodynamics associated with ink drying at printhead nozzles and contributes to the stability and reproducibility of inkjet printing.
PHYSICAL REVIEW APPLIED
(2023)
Article
Physics, Fluids & Plasmas
Yuki Wakata, Ning Zhu, Xiaoliang Chen, Sijia Lyu, Detlef Lohse, Xing Chao, Chao Sun
Summary: In this study, we investigate the Leidenfrost temperature for hot solid substrates with different thermal diffusivities and surface roughnesses. A phenomenological model is developed based on experimental data, which considers the thermal diffusivity of the solid substrate and establishes the relationship between surface roughness and vapor film thickness. The generality of this model is supported by experimental data for various liquids and solid substrates, providing a theoretical prediction of the Leidenfrost temperature and a comprehensive understanding of the Leidenfrost effect.
PHYSICAL REVIEW FLUIDS
(2023)
Article
Mechanics
You-An Lee, Detlef Lohse, Sander G. Huisman
Summary: We experimentally investigate the early-stage scalar mixing and transport with solvent exchange in a quasi-2D jet. Different modes of fluid supply, continuous injection and finite volume injection, are studied to analyze the starting jet and puff behaviors. The results show that the lack of continuous fluid supply in the puff leads to different characteristics in transport, entrainment, mixing, and nucleation.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2023)
Article
Mechanics
Nikolas O. Aksamit, Robert Hartmann, Detlef Lohse, George Haller
Summary: Mathematical developments in the theory of objective coherent structures have improved our understanding of the material organization of complex fluid flows. However, there is limited investigation into these objectively defined transport barriers in 3-D unsteady flows with complicated spatiotemporal dynamics. Our study utilizes simulations to uncover the interplay between different types of barriers in turbulent rotating Rayleigh-Bénard convection.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Jochem G. Meijer, Yanshen Li, Christian Diddens, Detlef Lohse
Summary: When an immiscible oil drop is immersed in a stably stratified ethanol-water mixture, it undergoes a transition from levitating to bouncing due to the oscillatory instability of the Marangoni flow on the drop's surface. The bouncing characteristics of the drop, such as jumping height and rising and sinking time, are studied in relation to the control parameters of drop radius, stratification strength, and drop viscosity. Experimental observations are backed by a simplified dynamical analysis and numerical simulations to verify the drag coefficients.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Rui Yang, Christopher J. Howland, Hao-Ran Liu, Roberto Verzicco, Detlef Lohse
Summary: The presence of salt affects the melt rate and shape evolution of ice in seawater. Numerical simulations and experiments are used to study ice melting in saline water. The melt rate of ice decreases and then increases with increasing salt concentration due to the competition between salinity-driven and temperature-driven buoyancy. A theoretical model based on force balance predicts the minimal salt concentration for ice melt rate, consistent with the data. Interplay between phase transitions and double-diffusive convective flows is revealed.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Physics, Fluids & Plasmas
Pallav Kant, Cesar Pairetti, Youssef Saade, Stephane Popinet, Stephane Zaleski, Detlef Lohse
Summary: We use experiments and numerical computations to study the fluid mechanical processes involved in the generation of bioaerosols during forceful respiratory maneuvers like coughing or sneezing. By performing analogous experiments on a cough machine, we observe the disintegration of a thin liquid film into small droplets and identify that aerosol generation is mediated by the formation of inflated baglike structures. The breakup of these bags is triggered by retracting holes on the surface, and the dynamics and stability of the liquid rims bounding these holes play a key role in the cascade from inflated bags to droplets. The viscosity of the fluid also affects the fragmentation process, with more viscous films producing smaller droplets.
PHYSICAL REVIEW FLUIDS
(2023)
Article
Mechanics
Qi Wang, David Goluskin, Detlef Lohse
Summary: Two-dimensional horizontally periodic Rayleigh-Benard convection between stress-free boundaries can exhibit two distinct types of states: roll states and windy states. Roll states consist of pairs of counter-rotating convection rolls, while windy states are dominated by a strong horizontally sheared wind that suppresses convection rolls. Windy states only occur when the Rayleigh number is sufficiently above the onset of convection.
JOURNAL OF FLUID MECHANICS
(2023)