Article
Engineering, Mechanical
Thomas Kerr, Adolfo Delgado
Summary: Critical Reynolds number is determined experimentally and defines the transition between laminar and turbulent flow. This paper presents the first critical Reynolds number for a Thrust Collar (TC) and demonstrates the increase in turbulence area with increasing spin speed and decreasing axial load. The study also introduces a Computational Fluid Dynamics (CFD) turbulence model that correlates well with experimental results.
TRIBOLOGY INTERNATIONAL
(2023)
Article
Mechanics
Aditi Sengupta, Prasannabalaji Sundaram, Vajjala K. Suman, Tapan K. Sengupta
Summary: Rayleigh-Taylor instability refers to the instability that occurs when the interface between two fluids of different densities is removed and the heavier fluid rests on top of the lighter fluid in the equilibrium state. This instability has been observed at various length scales, from nuclear fusion to astrophysical phenomena like supernova explosions. A non-overlapping parallel algorithm is used to simulate the three-dimensional Rayleigh-Taylor instability problem, providing insights into the vorticity creation and the dominance of viscous terms in the compressible flow.
Article
Mechanics
Zhe Wang, Bao Wang, Ding Weng, Caihua Wang, Na Sun, Jiadao Wang
Summary: This paper proposes a method to achieve underwater drag reduction through grooved surfaces and discusses the influence of bubble morphology on the drag reduction effect through numerical study. The results show that bubbles deform differently at various flow velocities, affecting the drag reduction effect of the gas layer formed on the surface.
Article
Mechanics
Jan Martin Nordbotten, Endre Joachim Lerheim Mossige
Summary: This paper addresses a fundamental and unsolved problem in fluid dynamics, which is to determine the behavior of rising bubbles and falling drops of one miscible liquid in another. The authors propose the first theory that predicts the velocity, volume, and composition of these drops at low Reynolds numbers. They derive a universal scaling law when diffusion out of the drop is negligible, and a parameter-free first-order ordinary differential equation when diffusion occurs. The results are validated against experimental data and the drop-scale parameters of the theory are identified.
Article
Engineering, Marine
Zhuang Kang, Caihong Yang, Cheng Zhang, Rui Chang, Yunhe Zhai
Summary: This study focused on the cross-flow vortex-induced vibration of a cylinder at high Reynolds numbers, improving turbulence models to simulate vibration characteristics and verifying the models' accuracy and applicability. The research provides theoretical references for studies on vortex-induced vibration at high Reynolds numbers.
JOURNAL OF MARINE SCIENCE AND TECHNOLOGY
(2021)
Article
Thermodynamics
Amir Mardani, Aslan Nazari
Summary: The Eddy Dissipation Concept (EDC) combustion model has gained attention for Moderate or Intense low oxygen Dilution (MILD) combustion. The study investigates the effect of characteristic frequency on the EDC model and performs parametric studies on the ratios of length and time scales. Results show the complexity of finding optimum model constants for different combustion conditions. A localized modulation method based on local variables is developed and applied on various burners, showing improved performance in burner simulation.
COMBUSTION AND FLAME
(2022)
Article
Astronomy & Astrophysics
V. Skoutnev, E. R. Most, A. Bhattacharjee, A. A. Philippov
Summary: The study derives scaling relations for the kinematic small-scale dynamo growth rate and amplification factor based on assumptions in the Rayleigh-Taylor instability. The results show discrepancies during different phases, allowing for quantitative prediction of magnetic energy amplification and determination of energy proportion with turbulent kinetic energy. The findings have implications for understanding magnetic energy evolution in laboratory and astrophysical scenarios.
ASTROPHYSICAL JOURNAL
(2021)
Article
Mechanics
Anton Burtsev, Wei He, Kai Zhang, Vassilios Theofilis, Kunihiko Taira, Michael Amitay
Summary: This paper investigates the linear modal instabilities of flow over untapered wings with aspect ratios AR = 4 and 8. Multiple unstable linear global modes have been identified and their dependence on geometric parameters has been examined. It is found that tip vortex effects dominate on the AR = 4 wing, while amplification of the leading mode is caused by wing tip recirculation on the AR = 8 wing. These findings are important for understanding flow stability and wake instability.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Kelsey Elfering, Shreyas Narsipur, Kenneth Granlund
Summary: The ratio between streamwise airfoil oscillations and the freestream velocity in the reduced frequency range relevant to unsteady applications has not been well studied. In this study, a parameter study was conducted to understand the dependence of circulatory lift on angle of attack, Reynolds number, surge amplitude, and reduced frequency. The results showed that unsteady lift is dependent on Reynolds number and reduced frequency, and the deviation between theory and experiment increases with increasing velocity fluctuation. A detailed study of surge amplitude of 0.5 was conducted to better understand this deviation.
Article
Mechanics
Fu-Ling Yang, You-An Chen, A. R. Premlata, Hsien-Hung Wei
Summary: This study demonstrates that slip asymmetry can significantly alter the swimming characteristics of self-propelled spherical squirmers. The asymmetry can affect the swimming velocity and stresslet of the squirmer, leading to the emergence of new swimming states. This research has important implications for the design of efficient artificial microswimmers.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Kostas D. Housiadas, Jeremy P. Binagia, Eric S. G. Shaqfeh
Summary: In this study, we investigated various aspects of the spherical squirmer model in weakly elastic fluids using large-scale numerical simulations and asymptotic methods. Our findings show that the low-Wi region plays a crucial role in enhancing speed and rotation rate in perturbation solutions.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Thermodynamics
Wenhua Duan, Weiyang Qiao, Weijie Chen, Xinyu Zhao
Summary: The effect of freestream turbulence (FST) on the boundary layer development of a high speed low pressure turbine under different Reynolds numbers (Re) is numerically investigated in this study. It is found that higher Re or FST level leads to earlier transition and Re has a greater effect than FST. The behavior of boundary layer development varies under different Mach numbers, with a separation bubble formed under low Mach number and no attachment detected under high Mach number. The mechanism for transition process differs under different FST levels and Mach numbers, with Kelvin-Helmholtz instability playing a dominant role under low FST and streamwise streaks becoming more important as Re increases under high FST.
JOURNAL OF THERMAL SCIENCE
(2023)
Article
Thermodynamics
Gokturk M. Ozkan, Husnu Egitmen
Summary: The study investigates the flow characteristics and turbulent structures around a NACA0012 airfoil at different Reynolds numbers and angles of attack. The results show significant changes in flow structures with increasing Reynolds number, and these changes have a significant impact on the drag polar of the NACA0012 airfoil.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2022)
Article
Mechanics
M. Kim, E. E. Essel, P. E. Sullivan
Summary: In this study, the effects of the synthetic jet actuator (SJA) on a NACA 0025 airfoil were investigated experimentally. The results showed that the SJA was effective in suppressing flow separation, and the excitation frequency had a significant impact on the control effectiveness.
Article
Physics, Multidisciplinary
Sukesh Roy, Joseph D. Miller, Gemunu H. Gunaratne
Summary: Studying turbulent flows is challenging due to the lack of high-frequency, high-resolution measurements. Using a burst-mode laser system in experiments can provide insights into small-scale structures and velocity dynamics in turbulent flows.
COMMUNICATIONS PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Jie Zhu, Jing Xue, Dan Sun, Wei Zhao, Chen Zhang, Xiaoqiang Feng, Kaige Wang
Summary: The interactions between DNA molecules and metal ions have significant effects on the current characteristics of DNA solutions, which is important for manipulating individual DNA molecules precisely.
Article
Chemistry, Multidisciplinary
Bingchen Che, Dan Sun, Chen Zhang, Jiaqing Hou, Wei Zhao, Guangyin Jing, Yuguang Mu, Yaoyu Cao, Liang Dai, Ce Zhang
Summary: Mechanically induced chromosome reorganization is important in transcriptional regulation, but the interplay between chromosome reorganization and transcription activities is complicated. By introducing DNA, packaging proteins, and transcription factor NF-KB into a fluidic chip with varying spatial confinement, it was found that strong nanoconfinement suppresses higher-order folding of protein-DNA complexes and leads to increased NF-KB binding. Overall, these results reveal a pathway of how intranuclear geometrical cues alter the open/closed state of a DNA-protein complex and affect transcription activities.
Article
Chemistry, Analytical
Rui Wan, Tianyun Zhao, Wei Zhao
Summary: In the field of autonomous driving, multi-modal 3D object detection using LiDAR and camera data is crucial but faces challenges in data fusion due to the differences between LiDAR points and camera images. This paper proposes PTA-Det, a method that combines a Pseudo Point Cloud Generation Network and a transformer-based Point Fusion Transition module to overcome these challenges. Experimental results on the KITTI dataset demonstrate the effectiveness of PTA-Det in achieving a car category mean average precision (mAP) of 77.88% with limited LiDAR input points.
Article
Polymer Science
Tong Wen, Chen Zhang, Yanyan Gong, Zezhi Liu, Wei Zhao, Yongjie Zhan, Ce Zhang, Kaige Wang, Jintao Bai
Summary: A high-durability photothermal slippery surface (HD-PTSS) was developed by using specific morphologic parameters and modified base materials doped with Fe3O4. The HD-PTSS achieved repeatability of over 600 cycles and its performance in terms of response time and transport speed was influenced by near-infrared ray (NIR) powers and droplet volume. The durability of the HD-PTSS was found to be closely related to its morphology and the recovering of a lubricant layer, with the Marangoni effect playing a key role.
Article
Chemistry, Analytical
Linhan Duan, Yueqiang Zhu, Haoxin Bai, Chen Zhang, Kaige Wang, Jintao Bai, Wei Zhao
Summary: A novel approach, called SVG-guided SLM LDW, combining two-photon absorption, SLM, and vector path-guided by scalable vector graphics, was developed for fast, flexible, and parallel nanofabrication. The independent control of three laser focuses with different paths optimized according to the SVG improved fabrication efficiency. The method enables the fabrication of complex structures on the nanoscale with a minimum structure width of 81 nm and a carp structure of 18.10 µm x 24.56 µm.
Article
Chemistry, Analytical
Yanxia Shi, Ming Zeng, Haoxin Bai, Shuangshuang Meng, Chen Zhang, Xiaoqiang Feng, Ce Zhang, Kaige Wang, Wei Zhao
Summary: In this investigation, the response of AC electrokinetic flow and the transition routes towards chaos and turbulence have been experimentally investigated. It is found that when the AC frequency f(f) > 30 Hz, the interface responds at both the neutral frequency of the basic flow and the AC frequency. However, when f(f) >= 30 Hz, the interface responds only at the neutral frequency of the basic flow. Periodic doubling and subcritical bifurcations have been observed in the transition of AC electrokinetic flow. We hope this investigation can promote our current understanding of the ultrafast transition process of electrokinetic flow from laminar state to turbulence.
Editorial Material
Chemistry, Analytical
Cuifang Kuang, Wei Zhao
Article
Chemistry, Analytical
Yanyan Gong, Ming Zeng, Yueqiang Zhu, Shangyu Li, Wei Zhao, Ce Zhang, Tianyun Zhao, Kaige Wang, Jiangcun Yang, Jintao Bai
Summary: Flow cytometry is a powerful technique for accurately distinguishing fluorescent-positive and negative populations. However, conventional flow cytometry discards informative results such as cell size, shape, morphology, and the distribution or location of labeled exosomes within unpurified samples. In this study, we propose a novel approach using an anti-diffraction light sheet with anisotropic feature to excite fluorescent tags. The proposed anti-diffraction light sheet flow cytometry (ADLSFC) can obtain more informative results than conventional methods, facilitating the distinction of target samples from complex backgrounds.
Article
Chemistry, Multidisciplinary
Xiaoliang Ji, Pingsong Jiang, Yichen Jiang, Hongyue Chen, Weiming Wang, Wenxuan Zhong, Xiaoqiang Zhang, Wei Zhao, Duyang Zang
Summary: In this work, a new approach using acoustic levitation combined with controlled liquid compensation is proposed to stabilize bubbles. The bubbles can remain stable and intact permanently due to the suppression of drainage by sound field and prevention of capillary waves by liquid compensation. It has been found that the acoustically levitated bubble shows a significantly enhanced particle adsorption ability. These results provide insight for the development of novel air-purification techniques without consuming any solid filters.
Article
Optics
Ziyi Gong, Yang Dang, Jie Zhu, Jiming Zheng, Chen Zhang, Wei Zhao, Kaige Wang
Summary: In situ, real-time, and non-destructive monitoring of nanomaterial synthesis is essential for the development and application of nanoscience and nanotechnology. Reflection interference spectroscopy technology was used to systematically monitor the synthesis process of a transparent (ZnCl2-ZnO)/NpAA composite film. By analyzing the curve of effective optical thickness with time, it was found that the synthesis process of ZnCl2-ZnO can be divided into three stages. Furthermore, films produced from ZnCl2 precursor solutions with different concentrations can be distinguished based on the characteristics of these three stages.
Article
Optics
Yueqiang Zhu, Kaige Wang, Jintao Bai, Wei Zhao
Summary: In this study, we report that the zero-order light caused by the pixelation effect of an SLM can be significantly eliminated by adjusting the pixel voltages. The experimental results demonstrate the improvement of the zero-order light suppression rate and modulation efficiency using this method.
Article
Biochemical Research Methods
Chen Zhang, Jiaqing Hou, Yang Zeng, Liang Dai, Wei Zhao, Guangyin Jing, Dan Sun, Yaoyu Cao, Ce Zhang
Summary: By fabricating a gradient nanochannel array on a slightly tilted nano-stage, we systematically investigate the dynamics of DNA translocation through nanoconfinement and its dependence on biomolecule size and geometrical features. Our results demonstrate that DNA undergoes conformational transition during translocation through nanochannels, driven either by electric field or flow, and the deformation energy required for translocation depends on both chemical environmental conditions and nanochannel dimensions. These findings suggest that optically fabricated gradient nanochannel arrays are suitable platforms for optimizing experimental conditions for biomedical applications.
Article
Automation & Control Systems
Bingchen Che, Dan Sun, Ningzhe Yan, Wei Zhao, Yonggang Liu, Guangyin Jing, Ce Zhang
Summary: Precise control of flow rate and pattern is crucial for studying the effects of shear force on cellular responses, biofluidic transport, and living matter in a flowing environment. This study proposes a novel microfluidic flow field generator capable of generating stable flow fields with the minimum interference from thermal noise. The flow generator outperforms existing methods in terms of low flow rate, temporal resolution of flow rate fluctuation, and the ability to provide complex flow patterns. It can also be easily integrated into fluidic chips, making it suitable for biological and biophysical studies requiring a well-defined flowing environment.
ADVANCED INTELLIGENT SYSTEMS
(2023)
Article
Optics
Zhao Wei, Chen Yu, Hu Zhongyan, Zhang Chen, Wang Kaige, Bai Jintao, Wang Guiren
Summary: Micro/nano-scale flow phenomena have wide applications in nature and engineering, and understanding the flow velocity fields is crucial for these applications. This paper introduces commonly used velocity measurement methods and provides a detailed introduction to a novel micro/nanofluidics velocity measurement technique called Laser Induced Fluorescence Photobleaching Anemometer (LIFPA). LIFPA has high spatial and temporal resolutions, making it suitable for measuring steady and unsteady flows on micro/nanoscales. The paper also summarizes the major achievements of LIFPA in observing micro/nano-scale flow phenomena and revealing their mechanisms. Suggestions for the further development of LIFPA are discussed.
ACTA PHOTONICA SINICA
(2022)
Article
Chemistry, Analytical
Yang Zeng, Rui Cao, Jie Zhu, Wei Zhao, Dan Sun, Ce Zhang
Summary: A methodology using dark field microscopy to capture live cell behavior is proposed, with minimal phototoxicity compared to traditional bright-field and fluorescence microscopy. The approach is suitable for long-term live cell imaging with super-high temporal resolution, as demonstrated by continuous exposure experiments on fibroblasts and hepatoma cells.
ANALYTICAL METHODS
(2022)
