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arXiv 2024年

作者： Ooshida, Takeshi Matsumoto, Takeshi Otsuki, Michio Department of Mechanical and Physical Engineering Tottori University Tottori680-8552 Japan Division of Physics and Astronomy Graduate School of Science Kyoto University Kyoto606-8502 Japan Graduate School of Engineering Science Osaka University Osaka Toyonaka560-8531 Japan

Correlations of the displacement field in a two-dimensional model colloidal liquid is studied numerically and analytically. By calculating the displacement correlations and the shear strain correlations from the numerical data of particle simulations, the displacement field is shown to have nontrivial correlations, even in liquids that are only slightly glassy with the area fraction as low as 0.5. It is suggested analytically and demonstrated numerically that the displacement correlations are more informative than the shear correlations: the former behaves logarithmically with regard to the spatial distance at shorter scales, while the corresponding information is missing from the shear correlations. The logarithmic behavior of the displacement correlations is interpreted as manifesting a long-lived aspect of the cage effect. Copyright © 2024, The Authors. All rights reserved.

关键词： Shear strain

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Mode coupling in converging Richtmyer-Meshkov instability of dual-mode interface

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Acta Mechanica Sinica 2020年第2期36卷 356-366页

作者： Zhangbo Zhou Juchun Ding Zhigang Zhai Wan Cheng Xisheng Luo Advanced Propulsion Laboratory Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230026China Mechanical Engineering Physical Science and Engineering DivisionKing Abdullah University of Science and TechnologyThuwal 23955-6900Saudi Arabia

The converging Richtmyer-Meshkov(RM)instability on single-and dual-mode N2/SF6 interfaces is studied by an upwind conservation element and solution element *** unperturbed case is first considered,and it is found that the shocked interface undergoes a long-term deceleration after a period of uniform *** evolution of single-mode interface at the early stage exhibits an evident nonlinearity,which can be reasonably predicted by the nonlinear model of Wang et al.(Phys Plasmas 22:082702,2015).During the deceleration stage,the perturbation amplitude drops quickly and even becomes a negative(phase inversion)before the reshock due to the Rayleigh-Taylor(RT)*** the reshock,the interface experiences a phase inversion again or does not,depending on the reshock *** growth of the second-order harmonic in the deceleration stage clearly reveals the competition between the RT effect and the *** dual-mode interfaces,the growth of the first mode(wavenumber k1)relies heavily on the second mode(wavenumber k2)due to the mode coupling ***,for cases where k2 is an even or odd multiple of k1,the growth of the first mode is inhibited or promoted depending on its initial amplitude sign and the phase difference between two basic waves,while for cases where k2 is a non-integer multiple of k1,the second mode has negligible influence on the first *** a systematic study,signs of perturbation amplitudes of the generated k2−k1 and k2+k1 waves are obtained for all possible dual-mode configurations,which are reasonably predicted by a modified Haan model(Phys Fluids B 3:2349-2355,1991).

关键词： Converging Richtmyer-Meshkov instability Dual-mode interface Mode coupling

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Bubble eruptions in a multilayer Hele-Shaw flow

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physical Review E 2022年第4期105卷 045101-045101页

作者： Ahmed Al Brahim Sigurdur T. Thoroddsen Mechanical Engineering Division of Physical Science and Engineering King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia Oil and Gas Networking Integrity Division Research and Development Center Saudi Aramco Thuwal 23955-6900 Saudi Arabia

We study the dynamical rearrangement of gravitationally unstable multilayer fluid inside the narrow vertical gap of a Hele-Shaw cell. Four layers of immiscible fluids are superposed inside the cell, which is subsequently turned over. We vary the fluid properties and the relative thicknesses of the layers. One of the layers is air, the others are immiscible liquids: olive oil, water-glycerin mixture, and perfluorohexane. The concentration of the glycerin-water mixture is used to vary its viscosity. We classify various different dynamics of stirring and breakthrough of adjacent layers. We note a prominent phenomenon, where an air finger breaks through the high-viscosity layer to erupt as a hemisphere into the lower-viscosity perfluorohexane layer above it. These eruptions have a periodic neck pinch-off accompanied with high-speed airflow which breaks up some of the low-viscosity liquid to eject a spray of fine droplets. We use high-speed video to characterize the details of the eruptions and how wetting, contact lines and three-dimensionalities play a key role. We also investigate the center-of-mass trajectories for each layer and notice counterflows, where the center of some layers can temporarily move against buoyancy. The top and bottom layers can interchange by channeling through the intermediate layers, which subsequently overturn on longer timescales. We also point out some unexpected dynamics occurring in the triple- and four-phase interactions. Specifically, droplet motions are as much affected by local viscosity as by the density gradients.

关键词： Displacement of immiscible fluids Drops & bubbles Rayleigh-Taylor instability

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Large-eddy simulation of Rayleigh-Bénard convection at extreme Rayleigh numbers

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arXiv 2022年

作者： Samuel, Roshan Samtaney, Ravi Verma, Mahendra K. Department of Mechanical Engineering Indian Institute of Technology Kanpur208016 India Mechanical Engineering Program Physical Science and Engineering Division King Abdullah University of Science and Technology Thuwal 23955 Saudi Arabia Department of Physics Indian Institute of Technology Kanpur208016 India

We adopt the stretched spiral vortex sub-grid model for large-eddy simulation (LES) of turbulent convection at extreme Rayleigh numbers. We simulate Rayleigh-Bénard convection (RBC) for Rayleigh numbers ranging from 106 to 1015 and for Prandtl numbers 0.768 and 1. We choose a box of dimensions 1:1:10 to reduce computational cost. Our LES yields Nusselt and Reynolds numbers that are in good agreement with the direct-numerical simulation (DNS) results of Iyer et al.1, albeit with a smaller grid size and at significantly reduced computational expense. For example, in our simulations at Ra = 1013, we use grids that are 1/120 times the grid-resolution as that of the DNS1. The Reynolds numbers in our simulations span 3 orders of magnitude from 1,000 to 1,700,000. Consistent with the literature, we obtain scaling relations for Nusselt and Reynolds numbers as Nu ∼ Ra0.317 and Re ∼ Ra0.497. We also perform LES of RBC with periodic side-walls, for which we obtain the corresponding scaling exponents as 0.343 and 0.477 respectively. Our LES is a promising tool to push simulations of thermal convection to extreme Rayleigh numbers, and hence enable us to test the transition to ultimate convection regime. © 2022, CC BY.

关键词： Large eddy simulation

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Electro osmotically flow of fourth-grade fluid in complex channel with porous medium and lubricated walls: applications in petroleum industry

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Waves in Random and Complex Media 2023年

作者： Nazeer, Mubbashar Pasha, Amjad Ali Hussain, Farooq Adil, Mohammad Mechanical Engineering Program Physical Science and Engineering Division King Abdullah University of Science and Technology Thuwal Saudi Arabia BUITEMS Quetta Pakistan KAUST Clean Combustion Research Center King Abdullah University of Science and Technology Thuwal Saudi Arabia Department of Mathematics Institute of Arts and Sciences Government College University Faisalabad Chiniot Campus Pakistan Aerospace Engineering Department King Abdulaziz University Jeddah Saudi Arabia

This article offers a distinct survey of a multiphase flow through a uniform channel. The electro-osmotic phenomenon is the main source of the flow. Fourth-grade fluid model is used as the base liquid which is suspended with metallic particles to form a bi-phase viscous suspension. Skin friction effects are tackled by employing lubrication effects on the opposite walls of the channel. Porous media is governed by the modified Darcy’s law and the Poisson differential equation is considered for electric double-layer effects. An approximate solution is achieved for the nonlinear fluid flow. The obtained findings are also compared with the existing literature for the limiting case. It is inferred that the shear thickness effects cause the momentum of the bi-phase flow to decline, gradually. However, the motion of the metallic particles is supported by the lubrication effects on the walls of the channel. © 2023 Informa UK Limited, trading as Taylor & Francis Group.

关键词： Porous materials

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Technology Roadmap for Flexible Sensors

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ACS NANO 2023年第6期17卷 5211-5295页

作者： Luo, Yifei Abidian, Mohammad Reza Ahn, Jong-Hyun Akinwande, Deji Andrews, Anne M. Antonietti, Markus Bao, Zhenan Berggren, Magnus Berkey, Christopher A. Bettinger, Christopher John Chen, Jun Chen, Peng Cheng, Wenlong Cheng, Xu Choi, Seon-Jin Chortos, Alex Dagdeviren, Canan Dauskardt, Reinhold H. Di, Chong-an Dickey, Michael D. Duan, Xiangfeng Facchetti, Antonio Fan, Zhiyong Fang, Yin Feng, Jianyou Feng, Xue Gao, Huajian Gao, Wei Gong, Xiwen Guo, Chuan Fei Guo, Xiaojun Hartel, Martin C. He, Zihan Ho, John S. Hu, Youfan Huang, Qiyao Huang, Yu Huo, Fengwei Hussain, Muhammad M. Javey, Ali Jeong, Unyong Jiang, Chen Jiang, Xingyu Kang, Jiheong Karnaushenko, Daniil Khademhosseini, Ali Kim, Dae-Hyeong Kim, Il-Doo Kireev, Dmitry Kong, Lingxuan Lee, Chengkuo Lee, Nae-Eung Lee, Pooi See Lee, Tae-Woo Li, Fengyu Li, Jinxing Liang, Cuiyuan Lim, Chwee Teck Lin, Yuanjing Lipomi, Darren J. Liu, Jia Liu, Kai Liu, Nan Liu, Ren Liu, Yuxin Liu, Yuxuan Liu, Zhiyuan Liu, Zhuangjian Loh, Xian Jun Lu, Nanshu Lv, Zhisheng Magdassi, Shlomo Malliaras, George G. Matsuhisa, Naoji Nathan, Arokia Niu, Simiao Pan, Jieming Pang, Changhyun Pei, Qibing Peng, Huisheng Qi, Dianpeng Ren, Huaying Rogers, John A. Rowe, Aaron Schmidt, Oliver G. Sekitani, Tsuyoshi Seo, Dae-Gyo Shen, Guozhen Sheng, Xing Shi, Qiongfeng Someya, Takao Song, Yanlin Stavrinidou, Eleni Su, Meng Sun, Xuemei Takei, Kuniharu Tao, Xiao-Ming Tee, Benjamin C. K. Thean, Aaron Voon-Yew Trung, Tran Quang Wan, Changjin Wang, Huiliang Wang, Joseph Wang, Ming Wang, Sihong Wang, Ting Wang, Zhong Lin Weiss, Paul S. Wen, Hanqi Xu, Sheng Xu, Tailin Yan, Hongping Yan, Xuzhou Yang, Hui Yang, Le Yang, Shuaijian Yin, Lan Yu, Cunjiang Yu, Guihua Yu, Jing Yu, Shu-Hong Yu, Xinge Zamburg, Evgeny Zhang, Haixia Zhang, Xiangyu Zhang, Xiaosheng Zhang, Xueji Zhang, Yihui Zhang, Yu Zhao, Siyuan Zhao, Xuanhe Zheng, Yuanjin Zheng, Yu-Qing Zheng, Zijian Zhou, Tao Zhu, Bowen Zhu, Ming Zhu, Rong Zhu, Yangzhi Zhu, Yong Zou, Guijin Chen, Xiaodong 08-03 Innovis Singapore 138634 Republic of Singapore Innovative Centre for Flexible Devices (iFLEX) School of Materials Science and Engineering Nanyang Technological University Singapore 639798 Singapore Department of Biomedical Engineering University of Houston Houston Texas 77024 United States School of Electrical and Electronic Engineering Yonsei University Seoul 03722 Republic of Korea Department of Electrical and Computer Engineering The University of Texas at Austin Austin Texas 78712 United States Microelectronics Research Center The University of Texas at Austin Austin Texas 78758 United States Department of Chemistry and Biochemistry California NanoSystems Institute and Department of Psychiatry and Biobehavioral Sciences Semel Institute for Neuroscience and Human Behavior and Hatos Center for Neuropharmacology University of California Los Angeles Los Angeles California 90095 United States Colloid Chemistry Department Max Planck Institute of Colloids and Interfaces 14476 Potsdam Germany Department of Chemical Engineering Stanford University Stanford California 94305 United States Laboratory of Organic Electronics Department of Science and Technology Campus Norrköping Linköping University 83 Linköping Sweden Wallenberg Initiative Materials Science for Sustainability (WISE) and Wallenberg Wood Science Center (WWSC) SE-100 44 Stockholm Sweden Department of Materials Science and Engineering Stanford University Stanford California 94301 United States Department of Biomedical Engineering and Department of Materials Science and Engineering Carnegie Mellon University Pittsburgh Pennsylvania 15213 United States Department of Bioengineering University of California Los Angeles Los Angeles California 90095 United States School of Chemistry Chemical Engineering and Biotechnology Nanyang Technological University Singapore 637457 Singapore Nanobionics Group Department of Chemical and Biological Engineering Monash University Clayton Australia 3800 Monash

Humans rely increasingly on sensors to address grand challenges and to improve quality of life in the era of digitalization and big data. For ubiquitous sensing, flexible sensors are developed to overcome the limitations of conventional rigid counterparts. Despite rapid advancement in bench-side research over the last decade, the market adoption of flexible sensors remains limited. To ease and to expedite their deployment, here, we identify bottlenecks hindering the maturation of flexible sensors and propose promising solutions. We first analyze continued...challenges in achieving satisfactory sensing performance for real-world applications and then summarize issues in compatible sensor-biology interfaces, followed by brief discussions on powering and connecting sensor networks. Issues en route to commercialization and for sustainable growth of the sector are also analyzed, highlighting environmental concerns and emphasizing nontechnical issues such as business, regulatory, and ethical considerations. Additionally, we look at future intelligent flexible sensors. In proposing a comprehensive roadmap, we hope to steer research efforts towards common goals and to guide coordinated development strategies from disparate communities. Through such collaborative

关键词： soft materials mechanics engineering flexible electronics conformable sensors bioelectronics human-machine interfaces body area sensor networks technology translation sustainable electronics

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Advanced Co3O4/CeO2 Ink for 3D Printing Layered Porous Electrodes to Boost Energy Density of Solid-State Supercapacitor

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Advanced Functional Materials 2025年

作者： Asghar, Ali Rashid, Muhammad Shahid Raza, Mohsin Hussain, Iftikhar Liu, Changyong Chen, Zhangwei Additive Manufacturing Institute Shenzhen University Shenzhen518060 China Department of Physical Science Physics Division College of Science Jazan University Jazan45142 Saudi Arabia Department of Mechanical Engineering City University of Hong Kong 83 Tat Chee Avenue Kowloon 999077 Hong Kong

The electrochemical properties are influenced by the surface-active sites and the porosity of materials in solid-state asymmetric supercapacitor (SSASC) devices. Transitioning from two-dimensional (2D) bulk to three-dimensional (3D)-printed electrodes for high-performance in SSASCs remains both exciting and challenging. This work, for the first time, introduces a novel oxygen-rich Co3O4/CeO2 nanocomposite (CCNC) ink with optimized rheological properties for constructing vertically aligned (3-layer and 5-layer) direct ink writing (DIW) 3D-printed SSASC electrodes with porous architectures. The 3D-printed 5-layer CCNC (3DP-5LCCNC) device demonstrates a remarkable mass loading of 18.61 mg cm−2, achieving an excellent areal capacitance of 7.09 F cm−2. The areal capacitance of 3DP-5LCCNC is ≈8.7 times greater than that of bulk CCNC (0.82 F cm−2) and 1.47 times higher than that of 3DP-3LCCNC (4.8 F cm−2). Furthermore, the 3DP-5LCCNC electrode exhibits an exceptional areal energy density of 2.366 mWh cm−2, significantly surpassing the bulk (0.273 mWh cm−2) and 3DP-3LCCNC (1.626 mWh cm−2) devices. This enhancement is attributed to the vertically aligned porous architecture, facilitating ion transport and enhances kinetic reactions. This work presents an innovative approach to ink formulation and provides a framework for designing high-performance 3D-printed electrodes with rapid ion transportation and outstanding electrochemical properties for advanced energy storage devices. © 2025 Wiley-VCH GmbH.

关键词： Supercapacitor

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High-speed imaging and coumarin dosimetry of horn type ultrasonic reactors: Influence of probe diameter and amplitude

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Ultrasonics Sonochemistry 2025年 119卷 107362页

作者： Viciconte, Gianmaria Sarvothaman, Varaha P. Guida, Paolo Truscott, Tadd T. Roberts, William L. Clean Energy Research Platform King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia Department of Mechanical Engineering Physical Science and Engineering Division King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia Splash Lab King Abdullah University of Science and Technology Thuwal 825001 23955-6900 Saudi Arabia

Ultrasound driven cavitation is widely used to intensify lab and industrial-scale processes. Various studies and experiments demonstrate that the acoustic energy, dissipated through the bubbles collapse, leads to intense physico-chemical effects in the processed liquid. A better understanding of these phenomena is crucial for the optimization of ultrasonic reactors, and their scale-up. In the current literature, the visual characterization of the reactor is mainly carried out with sonoluminescence and sonochemiluminescence. These techniques have limitations in the time resolution since a high camera exposure time is required. In this research, we proposed an alternative method, based on coumarin dosimetry to monitor the hydroxylation activity, and high-speed imaging for the visualization of the vapor field. By this approach, we aim to capture the structure and the dynamics of the vapor field and to correlate this with the chemical effects induced in the ultrasonic reactor. This characterization was carried out for four different ultrasonic probe diameters (3, 7, 14 and 40 mm), displacement amplitudes and processing volumes. Key findings indicate that the probe diameter strongly affects the structure of the vapor field and the chemical effectiveness of the system. The proposed methodology could be applied to characterize other types of ultrasonic reactors with different operating and processing conditions. © 2025 The Authors

关键词： Dosimetry

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Synthetic Data-Empowered Supervised Machine Learning Modeling for a Binary Fracture Risk Assessment from 2D-DXA Analysis

SSRN

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SSRN 2023年

作者： Choi, Heesun Quagliato, Luca Chung, Yoon-Sok Lee, Taeyong Division of Mechanical and Biomedical Engineering Ewha Womans University Seoul03760 Korea Republic of Division of Mechanical and Biomedical Engineering Graduate Program in System Health Science and Engineering Ewha Womans University Seoul03760 Korea Republic of Department of Endocrinology and Metabolism Ajou University School of Medicine Suwon16499 Korea Republic of

Background and Objectives: Bone fracture risk assessment for osteopenia and osteoporotic patients is essential for the adoption of early countermeasures and avoiding discomfort and hospitalization. Currently employed methodologies, such as FRAX®, provides a risk assessment over a five to ten years period without showing the main variables influencing the prediction nor how they can be targeted in the short term. Thus, a lesser black-box approach where the fracture risk can be assessed in real-time from a commonly employed analysis, id est the dual-energy X-ray absorptiometry (2D-DXA), would be of help to clinicians and patients alike. Accordingly, this study presents three real-time machine learning (ML) assessment models, with distinct complexity, architectures, and performances, capable of predicting a binary fracture risk based on a femur head-hip joint 2D-DXA scan. Methods: A ~10,000 adult Korean gathered between 2017 and 2021 and composed of ~90% female and ~10% male ranging from 50 to 99 years of age was considered. 10% of the data is relevant to subjects who experienced skeletal fractures, among which 245 cases are femur fractures. The 2D-DXA analyses of the femur head-hip joint region carried out on patients allowed collecting 23 parameters, including the patient’s age, BMI, and gender, associated with one binary variable, defined in terms of non-fracture (NFX) or fracture (FX), to be employed as the training dataset for the three ML models employed and optimized in this research. The 2D-DXA results’ database (DB) was employed to train three ML classifiers with a binary (NFX/FX) output layer, namely the Extreme Gradient Boosting (XGB), the K-Nearest Neighbor (KNN), and Deep Neural Network (DNN). To avoid overfitting due to the higher number of NFX data with respect to FX one, two features augmentation techniques based on the Synthetic Minority Over-sampling Technique (SMOTE) and Oversample using Adaptive Synthetic (ADASYN) oversamplers were employed. For all

关键词： Fracture

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Enhancing Gas Selectivity in Thin-Film Composite Carbon Molecular Sieve Membranes by Platinum Sputtering

SSRN

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SSRN 2025年

作者： Ogieglo, Wojciech Puspasari, Tiara Hu, Xiaofan Wehbe, Nimer Hassine, Mohamed Ben Aslam, Nabeel Kazmi, Syed N.R. Pinnau, Ingo Chemical Engineering Program Physical Science and Engineering Division King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia Imaging and Characterization Core Lab King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia Nanofabrication Core Lab King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia

We present a novel approach to significantly boost gas-pair selectivity of thin-film composite (TFC) carbon molecular sieve (CMS) membranes by sputtering platinum on the surface of the CMS precursor polymer prior to pyrolysis. A polyimide of intrinsic microporosity (PIM-PI), 6FDA-HTB, was selected as the CMS precursor which had previously been shown to transform into an excellent CMS membrane material at moderate pyrolysis temperatures (550 – 600 °C). Deposition of Pt at high ion currents combined with subsequent pyrolysis at 550 °C leads to the development of an ultrathin (10-20 nm thick) Pt/CMS intermix layer consisting of a CMS matrix with a large volume fraction of embedded, fused Pt nanoparticles. The Pt phase seems to stabilize the micropores of the intermixed CMS phase as well as limit the undesired impact of defects leading to a dramatic enhancement of gas-pair selectivity of the modified TFC CMS membranes (e.g. H2/CH4 > 1100, CO2/CH4 ~100, O2/N2 ~ 11) which represent improvements of 3300, 370, and 100% in comparison to the non-Pt-sputtered CMS control membranes. This novel, simple and effective procedure may be extendable to other types of CMS polymer precursors, membrane supports, alternative sputtering metals and the deposition parameters can be easily tuned to balance the membrane permeance against the desired selectivity. © 2025, The Authors. All rights reserved.

关键词： Micropores

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