Article
Chemistry, Physical
Yijiang Yu, Michael D. Graham
Summary: This study indicates a compact-stretch transition in the dynamics of thin elastic sheets exposed to extensional flow, similar to the coil-stretch transition in long linear polymers. Different sheet shapes exhibit different behaviors in planar and biaxial flows, with bistable behavior observed in a certain parameter regime, where both weakly stretched and strongly stretched states can be found depending on initial conditions.
Article
Physics, Multidisciplinary
Antonio Pol, Riccardo Artoni, Patrick Richard, Paulo Ricardo Nunes da Conceicao, Fabio Gabrieli
Summary: The kinematics and shear-induced alignment of elongated particles in confined, heterogeneous flow conditions were experimentally investigated. The results show that the slip velocity at the bottom is influenced by the particle shape, while rotations are highly frustrated by particle shape with more elongated particles showing a lower angular velocity. The proneness of a particle to rotate is observed to be shear-rate dependent, with a stronger inhibition in low shear zones. The average particle orientation is slightly tilted downwards and decreases with particles' elongation. Orientational order increases with particles' elongation and is not affected by the applied confinement, except for a weak decrease in regions of higher shear rate. At the particle-scale, angular velocity fluctuations are strongly correlated with local particle orientation, with particles strongly misaligned with the preferential particles' orientation rotating faster. This correlation becomes stronger for more elongated particles and is almost unaffected by the applied confinement.
NEW JOURNAL OF PHYSICS
(2022)
Article
Mechanics
Vikash Pandey, Dhrubaditya Mitra, Prasad Perlekar
Summary: A direct numerical simulation study of buoyancy-driven bubbly flows in the presence of large-scale driving that generates turbulence reveals that increasing turbulence intensity leads to more curved bubble trajectories and decreased average rise velocity. The energy spectrum of the flow exhibits pseudo-turbulence scaling for small length scales and Kolmogorov scaling for larger scales. A scale-by-scale energy budget analysis helps understand the scaling behavior seen in the spectrum, with statistical properties consistent with experiments on turbulence modulation by air bubbles in water despite the weak buoyancy of the bubbles.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Cong Li, Jiping Huang, Weijuan Fu, Ge Song, Yingli Chang, Zigen Song
Summary: This study conducted numerous numerical simulations in a sealed cylinder to investigate the morphological evolution of internal vortex breakdowns (VBs) with different aspect ratios, focusing on the axial lengths and trajectories of VBs. The research revealed that the number of VBs in rotating fluid was not fixed for the same aspect ratio, impacting the complexity of VB evolution. Using the theory of swirl decay, the formation and stair-step changes of VBs were explained from an energy perspective, shedding light on a new class of fluid behavior that may contribute to vortex control.
Article
Nanoscience & Nanotechnology
Loren D. Alegria, Charlotte G. L. Bottcher, Andrew K. Saydjari, Andrew T. Pierce, Seung Hwan Lee, Shannon P. Harvey, Uri Vool, Amir Yacoby
Summary: The study of tunnel spectroscopy in mesoscopic superconductors under high electric fields revealed the unexplored phenomenon of high-energy QP injection and its impact on critical current, as well as the observation of the superconductor switching to a normal state under the influence of electric field.
NATURE NANOTECHNOLOGY
(2021)
Article
Chemistry, Multidisciplinary
Fan Li, Stoyan K. Smoukov, Ivan Korotkin, Makoto Taiji, Sergey Karabasov
Summary: Structured water near surfaces plays important roles in nonclassical crystallization, biomineralization, and restructuring of cellular membranes. High-speed AFM can now detect piconewton forces in microseconds, but MD simulations are needed for accurate predictions due to the limitations of continuum water models. However, MD simulations can only evolve over tens of nanoseconds, so new methods are needed to bridge the gap.
Article
Chemistry, Physical
Max Crowder, Frozan Tahiry, Isabel Lizarraga, Stephanie Rodriguez, Nathaly Pena, Arun K. Sharma
Summary: In this study, the dynamics of water molecules inside reverse micelles were analyzed using molecular dynamics simulations. The results showed that as the size of the reverse micelles increased, the residence time and diffusion coefficients of water molecules became more similar to those of bulk water. This supports the conclusion that water molecules in reverse micelles adopt a three-layer model of core-intermediate-interface.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Mechanics
Zvi Rusak, Akashdeep Singh Virk
Summary: This study presents a small-disturbance model for a two-dimensional transonic gas flow around a thin airfoil, investigating the impact of gas thermodynamic modeling on flow behavior. Results show that transonic flows are independent of gas modeling at low subcritical conditions, but are sensitive to gas modeling and K-G variations at near-critical and supercritical conditions.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Physics, Fluids & Plasmas
Zhiqiang Shen, Jihong Ma, Jan-Michael Y. Carrillo, Wei-Ren Chen, Bobby G. Sumpter, Yangyang Wang
Summary: The study of liquid dynamics at mesoscopic scales is challenging, but modern computational techniques and novel experimental methods have enabled a better understanding of the complexity and mechanisms involved. Through the spatiotemporal mapping method, one can comprehensively analyze the characteristics of mesoscopic dynamics in liquids, revealing the roles of various mechanisms such as molecular relaxation, hydrodynamic modes, and nonhydrodynamic excitations.
Article
Chemistry, Physical
Seongchul Park, Juhyang Shin, Hojeong Yoon, Manho Lim
Summary: The rotational isomerization of 1,2-disubstituted ethyl radical derivatives in solution has been investigated, and the rotational time constants have been measured. This finding contributes to a better understanding of the reaction mechanism involving these radicals and provides insights into the formation of stereoisomers of compounds produced via the intermediates.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Mechanics
Shangwen Gao, Chengbin Zhang, Yingjuan Zhang, Qiang Chen, Bo Li, Suchen Wu
Summary: In this study, four typical and widely used improved schemes for the pseudopotential lattice Boltzmann (LB) method are analyzed and compared. Theoretical and numerical results show that the three previous schemes are specific forms of the last one, which helps further understand the improvements of these LB models for achieving thermodynamic consistency. The modified calculation method is confirmed to be more accurate through numerical results.
Article
Mechanics
Chenyang Wang, Xiao Wu, Pengfei Hao, Feng He, Xiwen Zhang
Summary: The study introduces a new model to simulate the freezing process of droplets, finding that the temperature of droplets jumps during the recalescence stage and is almost unaffected by external factors. Additionally, the volume and surface properties of droplets affect the solidification time and the final shape of the ice.
Article
Physics, Multidisciplinary
Supun S. Mohottalalage, Manjula Senanayake, Joel T. Clemmer, Dvora Perahia, Gary S. Grest, Thomas O'Connor
Summary: The response to elongational flow is important in soft matter and has implications in various technologies. In this study, the effects of associating groups on the structure and dynamics of linear polymer melts under uniaxial elongation were investigated using molecular dynamics simulations.
Article
Multidisciplinary Sciences
Zhongyu Zheng, Ran Ni, Yuren Wang, Yilong Han
Summary: Critical-like behaviors have been observed in translational and rotational degrees of freedom of monolayers of monodisperse colloidal ellipsoids without crystalline orders. The Ising-like criticality is found at the ideal glass transition point phi(0), while a dynamic criticality is observed at the mode-coupling critical point phi(c) for fast-moving clusters, reflecting the thermodynamic and dynamic nature of glass transition phenomena.
Article
Multidisciplinary Sciences
Timofey Kozhukhov, Tyler N. Shendruk
Summary: Coarse-grained, mesoscale simulations are essential for studying soft condensed matter. We introduce an algorithm to simulate active nematics, which can model complex systems in an active medium. The method exhibits the key characteristics of active nematic turbulence and active particle models.
Article
Engineering, Electrical & Electronic
Cletus Jaimon, S. Kumar Ranjith
MICROSYSTEM TECHNOLOGIES-MICRO-AND NANOSYSTEMS-INFORMATION STORAGE AND PROCESSING SYSTEMS
(2017)
Article
Thermodynamics
R. Simhadri Rajesh, P. T. Naveen, K. Krishnakumar, S. Kumar Ranjith
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2019)
Article
Materials Science, Characterization & Testing
Blossom Treesa Bastian, N. Jaspreeth, S. Kumar Ranjith, C. V. Jiji
NDT & E INTERNATIONAL
(2019)
Article
Biochemical Research Methods
A. Arjun, R. R. Ajith, S. Kumar Ranjith
Article
Physics, Applied
K. Mahesh, S. Kumar Ranjith, R. S. Mini
Summary: The study introduces a method of utilizing deep neural networks for reverse designing low-frequency sound absorbers, successfully designing an acoustic absorber with broadband characteristics and demonstrating its sound absorption effect of over 90% in a specific frequency band.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Thermodynamics
M. G. Arun, D. Dilip, S. Kumar Ranjith
Summary: Superhydrophobic microchannels exhibit reduced frictional flow resistance due to entrapped air on their surface micro texture, but this air may negatively impact heat transfer performance. The shape of the menisci formed at the liquid-gas interface in these channels affects the thermo-hydraulic performance, with increased shear-free fraction leading to improved performance and concave menisci showing uniform Nusselt number. Ribbed hydrophobic channels outperform classical channels with uniform heating within a certain protrusion angle range.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Computer Science, Interdisciplinary Applications
K. Mahesh, S. Kumar Ranjith, R. S. Mini
Summary: This paper proposes an algorithm based on deep convolutional autoencoder network for the inverse design of a low-frequency acoustic absorber. A hybrid sound-absorber configuration with Helmholtz resonators, curvy neck, and microperforated panel is suggested and its geometrical properties are inversely forecasted. By using the effective medium theory and the electro-acoustic analogy, a mathematical model is established to evaluate the absorption characteristics of the introduced geometry. The proposed inverse technique is successfully applied to both standard and complex geometrical setups, achieving high accuracy without pre-design information on absorber geometry. The developed absorber models with deep sub-wavelength thickness and wide absorption spectra have great potential in noise reduction applications.
ENGINEERING WITH COMPUTERS
(2023)
Article
Thermodynamics
Joseph Amal, K. K. Krishnaram, S. Kumar Ranjith
Summary: This numerical investigation analyzes the thermo-hydraulic characteristics of a uniform flow past an inclined hydrophobic cylinder under steady state condition. The Navier-slip boundary condition is used to mimic the fluid interaction with hydrophobic surface. The study investigates the effect of inclination and hydrophobicity for different Reynolds numbers. The results show that as hydrophobicity increases, the drag force decreases near the Stokes regime. However, the effect diminishes at higher Reynolds numbers. Similarly, the incident angle and aspect ratio of the spheroid are inversely proportional to the hydrodynamic resistance. The presence of partially slipping hydrophobic surface also alters the heat transport.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2023)
Article
Multidisciplinary Sciences
K. Mahesh, P. P. Anoop, P. Damodaran, S. Kumar Ranjith, R. S. Mini
Summary: An acoustic metasurface composed of pie-sliced resonator segments is proposed for ultra-low-frequency noise cancellation. Multiple types of sound absorbers with different unit cell designs are fabricated and tested. By manipulating the geometrical features, the absorption performance in the ultra-low-frequency regime can be modified.
ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING
(2023)
Article
Rehabilitation
J. P. Akhil, R. R. Ajith, S. Kumar Ranjith
Summary: This article proposes a new wheelchair model that combines independent toilet accessibility, transferability, and indoor maneuverability. Through a field survey and design analysis, a multipurpose self-propelled wheelchair is developed. User feedback and skill tests confirm that the design meets the requirements for indoor mobility.
DISABILITY AND REHABILITATION-ASSISTIVE TECHNOLOGY
(2023)
Article
Mechanics
K. Nandakumar Chandran, P. T. Naveen, R. Abhilash, S. Kumar Ranjith
Summary: This study numerically examines droplet impact dynamics on hydrophobic surfaces under different wettability and impact conditions, identifying sticking, bouncing, and splitting regimes. The simulations are validated against experimental results, showing good agreement and a significant reduction in computational time.
INTERNATIONAL JOURNAL OF COMPUTATIONAL FLUID DYNAMICS
(2021)
Article
Thermodynamics
Liju Ulahannan, K. Krishnakumar, Anjan R. Nair, S. Kumar Ranjith
Summary: Extensive investigations have been conducted on the thermo-hydrodynamics of nanofluid droplets interacting with heated and non-heated flat surfaces, with a focus on the influence of nanoparticle shape on droplet impingement dynamics on heated flat surfaces. The study observed different impact dynamics, Leidenfrost temperatures, residence time, spread factor, and retraction height between nanofluids and base pure fluid. Detailed analyses were carried out for various Weber numbers and surface superheat values, showing significant differences compared to de-ionized water.
EXPERIMENTAL AND COMPUTATIONAL MULTIPHASE FLOW
(2021)
Article
Thermodynamics
M. P. Joseph, G. Mathew, G. G. Krishnaraj, D. Dilip, S. Kumar Ranjith
EXPERIMENTAL AND COMPUTATIONAL MULTIPHASE FLOW
(2020)
Proceedings Paper
Engineering, Electrical & Electronic
Steffin Varghese, Shimna Shafeek, Ranjith S. Kumar, R. S. Mini
2017 INTERNATIONAL CONFERENCE ON ELECTRICAL AND COMPUTING TECHNOLOGIES AND APPLICATIONS (ICECTA)
(2017)
