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Motion of a rigid particle in the lid-driven cavity flow

Chinese Physics B 2025年第3期34卷 448-459页

作者： Fan Yang Zhe Yan Wencan Wang Ren Shi School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China

The motion of an elliptical rigid particle in a lid-driven cavity flow was numerically simulated using the immersed boundary lattice Boltzmann method(IB-LBM).The effects of the particle's initial orientation angle,initial position,aspect ratio,and size on the motion characteristics were *** computational results indicate that the particle's motion undergoes two distinct stages:a starting stage that involves moving from the release position to a limit cycle,and a periodic stage that involves moving on the limit *** initial orientation of the particle has a minimal impact on both stages of *** contrast,the time it takes for the particle to reach the limit cycle may vary depending on the release ***,particles with a larger aspect ratio exhibit a greater maximum velocity magnitude;an increase in particle size causes the particle trajectory to contract more toward the center of the cavity,decreasing the centrifugal force experienced by the particle.

关键词： lattice Boltzmann methods immersed boundary method elliptical rigid particle lid-driven cavity flow

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Influence of Soil-Structure Interaction Models on the Dynamic Responses of An Offshore Wind Turbine Under Environmental Loads

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China Ocean engineering 2023年第2期37卷 218-231页

作者： TANG Hong-ming YUE Min-nan YAN Yang-tian LI Zhi-hao LI Chun NIU Kai-lun School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China

Offshore wind turbines(OWTs) suffer wind, wave and earthquake loads. The investigation of OWTs' dynamic response under environmental loads is essential for structural safety assessment. The soil-structure interaction(SSI)significantly affects the responses of OWT under environmental loads. However, there is few systematic research about the difference in the dynamic response of different SSI models under environmental loads. In order to solve the problem, the OWT is modeled by shell element, and several SSI models are built. The wind, wave and earthquake loads are taken into account. Moreover, the dynamic response, fatigue and buckling analysis are performed by ANSYS. The results indicate that SSI cannot be ignored in the dynamic response of the OWT under wind and wave loads. The SSI can decrease the displacement response of the OWT by 19% under wind and wave loads and reduce the fatigue damage of the pile. Multi-layer SSI can strongly influence the OWT's dynamic response under wind and wave loads or earthquake-only load. The vertical earthquake load increases the dynamic response in three ***, in order to simulate real environment, multi-layer SSI, soil damping and vertical SSI must be considered to evaluate the displacement response of the OWT under wind, wave and earthquake loads. The earthquake and gravity loads can cause more obvious response of the OWT than that of only wind and wave loads. The top and bottom of the tower are prone to occur buckling.

关键词： OWT soil structure interaction earthquake dynamic analysis structural damage

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3D particle streak velocimetry by defocused imaging

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Particuology 2023年第1期72卷 1-9页

作者： Xiangrui Dong Xiaoxiao Wang Wu Zhou Fangting Wang Xinran Tang Xiaoshu Cai School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering Shanghai 200093China

Particle streak velocimetry (PSV) has become one of the important branches of flow filed measurements. It extracts velocity information from particle trajectories captured by single frame long exposure images. Since the defocus of moving particle is inevitable during a long exposure time and under a large magnification, a novel three-dimensional (3D) velocity measurement method named defocusing particle streak velocimetry (DPSV) is proposed in this paper. On the one hand, an extension from two-dimensional (2D) to 3D velocity measurement with a monocular system is carried out. The depth information of the particle, which reflects the position in the third dimension, is indicated by the defocusing degree (characteristic parameter σ) of the particle images. The variation of σ along the trajectory is recognized by surface fitting of the gray value distribution of particle images, assuming that σ varies linearly along the trajectory. On the other hand, based on the linear fitting for the straight trajectory, an arc fitting model is developed for curved trajectories which are commonly captured in turbulent flow. The relationship between σ and the particle depth position z is experimentally calibrated using a LED light and a diaphragm. Finally, the DPSV method is verified in a submerged jet flow field as well as in a microchannel flow field to obtain the 3D velocity field with single monocular system.

关键词： Defocusing particle streak velocimetry Curve trajectory Three-dimensional velocity Gray value distribution

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Insight into the interaction between water and surfactant aerosol particles based on molecular dynamics simulations

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Particuology 2023年第6期77卷 128-135页

作者： Chao Zhang Zhichao Zhang Longxiang Bu Yang Yang Wei Xiong Yueshe Wang School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and TechnologyShanghai200093China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an710049China

The ubiquitous surfactant significantly influences the hygroscopic growth of atmospheric aerosol ***,knowledge on the morphology of surfactant particles after the adsorption of water is *** this study,the interaction between water and particles composed of surface active malonic acid(MA)or adipic acid(AA)are simulated based on the molecular dynamics *** key point is the combined effect of temperature and water content on the structural properties of particles and the surface propensity of surfactants at the equilibrium *** show that demixed structure 1 with the adsorption of water clusters on acid grain,mixed structure and demixed structure 2 with acids coating on water droplet can be *** temperature increasing from 160 K to 330 K the surface propensity of MA and AA increases first and then *** the standard atmospheric temperature(280-330 K),the surface propensity of MA and AA increases with increasing water content and alkyl group,and its sensitivity to temperature and water content varies ***,all surfactants at the particle surface orient their hydrophobic groups toward the *** findings improve our insight into the surfactant partitioning and further assist in more accurate prediction of the particle hygroscopic growth.

关键词： Aerosol particles Surfactant Surface propensity Hygroscopic growth Molecular dynamics

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Three-dimensional numerical study on flow control of two-phase flow around a cylinder with an auxiliary miniature cylinder

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PHYSICS OF FLUIDS 2025年第4期37卷

作者： Xie, Yunqi Hu, Yu Huang, Shengxian Wang, Ying Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai Peoples R China

In ocean engineering, studying the phenomena of flow separation, vortex shedding, and particle deposition around blunt bodies is crucial, as these factors significantly affect the performance, stability, and lifespan of marine structures. This study, conducted under realistic marine conditions with a Reynolds number of Re = 2.5 x 10(5), and accounting for gravitational effects, first investigates the impact of installing auxiliary miniature cylinders at the front edge of the primary cylinder with different gap ratios, aiming to identify the optimal gap ratio. Subsequently, trailing-edge miniature cylinders are added for comparative analysis. This study also explores the effects of vibrating upstream miniature cylinders. Additionally, it examines the influence of auxiliary miniature cylinders on particle distribution in the wake region under particle-laden flow. The results indicate that miniature cylinders at specific gap ratios significantly reduce the drag and lift coefficients of the primary cylinder, suppress vortex shedding, optimize wake structures, and weaken the horseshoe vortex. While vibrating cylinders reduce vortex suppression, high-frequency vibrations contribute to greater drag reduction. Upstream miniature cylinders reduce the influence of vortex structures in the wake but increase sediment deposition. A dual-cylinder configuration is the most effective method for controlling sediment concentration distribution at the base of the primary cylinder.

关键词： Vortex flow

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Polarized imaging dynamic light scattering for simultaneous measurement of nanoparticle size and morphology

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Particuology 2024年第2期85卷 213-223页

作者： Bingyao Wang Tianyi Cai Xiaoshu Cai Wu Zhou Zeqi Liu Schoolof Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093China Jiaxing MeaParTech Instrument Technology Co. LtdZhejiang314000China

The performance of nanoparticles is often affected by particle size and ***,electron microscopy or atomic force microscopy is typically utilized to determine the size and morphology of ***,there are issues such as difficult sample preparation,long processing times,and challenges in quantitative ***,it is of great significance to develop a fast,accu-rate,and statistical method to measure the size and morphology of *** this study,a new method,called polarized imaging dynamic light scattering(PIDLS),is *** nanoparticles are irradiated with a vertical linearly polarized laser beam,and a polarization camera collected the dynamic light scattering images of particles at four different polarization directions(0°,45°,90°,and 135°)at a scattering angle of 90°.The average particle size and distribution are obtained using the imaging dy-namic light scattering method at 0°polarization direction,and the morphology of the particles is ob-tained based on the depolarization patterns of the scattered *** optical sphericityΦis defined based on the degree of linear polarization(DoLP).It is also implemented for the quantitative evaluation of the sphericity of the nanoparticles,including spherical,octahedral,nanoplate,nanorod,and linear *** with the Poincarésphere parameterψ,the morphology of the nanoparticles can be roughly *** addition,PIDLS enables the measurement of particle size and morphology distributions simultaneously for evaluating the uniformity of *** effectiveness of PIDLS is verified by the measurement of five kinds of industrial titanium dioxide as well.

关键词： Imaging dynamic light scattering Polarized light scattering Non-spherical nanoparticles Morphology Online measurement

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Reconstruction of particle distribution for tomographic particle image velocimetry based on unsupervised learning method

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Particuology 2024年第10期93卷 349-363页

作者： Duanyu Zhang Haoqin Huang Wu Zhou Mingjun Feng Dapeng Zhang Limin Gao School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering University of Shanghai for Science and TechnologyShanghai200093China National Key Laboratory of Aerodynamic Design and Research Northwestern Polytechnical UniversityXi'an710072China

The development of deep learning has inspired some new methods to solve the 3D reconstruction problem for Tomographic Particle Image Velocimetry (Tomo-PIV). However, the supervised learning method requires a large number of data with ground truth as training information, which is very difficult to gather from experiments. Although synthetic datasets can be used as alternatives, they are still not exactly the same with the real-world experimental data. In this paper, an Unsupervised Reconstruction Technique based on U-net (UnRTU) is proposed to reconstruct volume particle distribution explicitly. Instead of using ground truth data, a projection function is used as an unsupervised loss function for network training to reconstruct particle distribution. The UnRTU was compared with some traditional algebraic reconstruction algorithms and supervised learning method using synthetic data under different particle density and noise level. The results indicate that UnRTU outperforms these traditional approaches in both reconstruction quality and noise robustness, and is comparable to the supervised learning methods AI-PR. For experimental tests, particles dispersed in cured epoxy resin are moved by an electric rail with a certain speed to obtain the ground truth data of particle velocity. Compared with other algorithms, the reconstructed particle distribution by UnRTU has the best reconstruction fidelity. And the accuracy of the 3D velocity field estimated by UnRTU is 12.9% higher than that from the traditional MLOS-MART algorithm. It demonstrates significant potential and advantages for UnRTU in 3D reconstruction of particle distribution. Finally, UnRTU was successfully applied to the high-speed planar cascade airflow field, demonstrating its applicability for measuring complex fluid flow fields at higher particle density.

关键词： Tomographic particle image velocimetry 3D reconstruction Unsupervised learning Convolutional neural network

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Comparison of three-component co-pyrolytic char and corn straw biochar for assisting water electrolysis to achieve efficient hydrogen production

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JOURNAL OF power SOURCES 2025年 630卷

作者： Chen, Xinyue Ying, Zhi Sun, Hao Zheng, Xiaoyuan Dou, Binlin Cui, Guomin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

Biochar-assisted water electrolysis (BAWE) technology can effectively reduce the energy consumption for hydrogen production and achieve the upcycling of biochar. However, the identification of highly active and efficient biochar remains a pressing need for BAWE process. Herein, we initially employ the three primary components of cellulose, hemicellulose and lignin in corn straw and the raw corn straw to produce char and biochar, respectively, followed by a systematic comparison of the biochar oxidation reaction (BOR) of char and biochar in BAWE process. The char exhibits superior BOR kinetics compared to biochar, mostly attributed to its exposed surface and porous structure. But HCl pickling of biochar moderately removes ash and enhances hydrophilicity, thereby improving BOR kinetics. For both char and biochar-assisted water electrolysis at 150 mA cm-2, nearly 100 % of Faradaic efficiency for hydrogen production is reached;both char and biochar are enriched with oxygen-containing functional groups such as -OH, C-O, and C=O, alongside enhanced hydrophilicity. Furthermore, the presence of CO2, 2 , CO, and O22 in anodic mixed gas confirms the competition between BOR and oxygen evolution reaction. This work establishes a foundation for efficient hydrogen pro- duction and electrochemical modification of biochar in BAWE process.

关键词： Biochar-assisted water electrolysis (BAWE) Hydrogen Biochar oxidation reaction (BOR) Kinetics

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Effects of pretreatment on biochar oxidation reaction and hydrogen production in lignocellulosic biochar-assisted water electrolysis

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2025年 99卷 752-760页

作者： Sun, Hao Ying, Zhi Chen, Xinyue Zheng, Xiaoyuan Dou, Binlin Cui, Guomin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

Substituting the oxygen evolution reaction in water electrolysis with the thermodynamically more favorable biochar oxidation reaction (BOR) constitutes biochar-assisted water electrolysis (BAWE), presenting a promising strategy for energy-efficient hydrogen production and high-value utilization biochar. Nevertheless, the BOR suffers from the sluggish kinetics and ambiguous selectivity with respect to ungraded biochar. Herein, we demonstrate the effects of elution treatment on pyrolytic lignocellulosic biochar concerning BOR kinetics and hydrogen production, as well as the efficiency of electrooxidized biochar in Cr(VI) removal. The original lignocellulosic biochar washed by alkali, acid, and water exhibited an improved BOR kinetics. Notably, the moderate water washing favored the removal of ash and soluble substances, thereby exposing more easily oxidizable functional groups such as C-OH and COOH, which substantially enhanced BOR kinetics. The waterwashed biochar-assisted water electrolysis achieved a Faradaic efficiency of 99.5% for hydrogen production at 50 mA cm-2, necessitating lower cell voltages compared to unwashed biochar. Water elution pretreatment also promoted the sufficient oxidation of biochar during electrolysis, with enriched oxygen-containing functional groups like C-O contributing to an increase in Cr(VI) removal rate from 20.81% to 65.10%. This work offers strategies for achieving efficient biochar upgrading and hydrogen production in the BAWE process.

关键词： Biochar-assisted water electrolysis Elution treatment Electrooxidation Hydrogen production Cr(VI) adsorption

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Meniscus-guided 3D printing with material supplied by the intrinsic capillary replenishment flow: Printing success rate, printed structure size adjustment, and microscale functional device fabrication

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JOURNAL OF MATERIALS PROCESSING TECHNOLOGY 2025年 339卷

作者： Cai, Rongze Wang, Haiyang Han, Xueqing Wang, Dongmin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

Meniscus-guided 3D printing is a microscale ink-based 3D printing technique, which features ease of operation and can print micro/nano functional devices of multiple types of materials at a low cost. However, the customized microscale functional device fabrication challenge remains, because the critical printing conditions for successful printing are complex. Whether the printed device efficiency depends on printing conditions is unclear. Our study shows that there exist clogging and terminated critical pulling speeds in meniscus-guided 3D printing with material supplied by the evaporation-induced capillary replenishment flow, where only the pulling speed is within this range 3D printing could be successfully implemented. The printable ink viscosity can be higher than the previously reported if the pulling speed criterion is satisfied. The critical pulling speeds and the interval between them decrease with the micropipette diameter or ambient humidity. A more comprehensive formulation than the literature reported ones describing the dependence of the 3D-printed micropillar diameter on the micropipette pulling velocity and diameter is derived, which agrees well with the experimentally printed micropillar diameters under different conditions and indicates that 3D-printed micropillar diameter adjustment is governed by the meniscus shape and its evaporation rate. Based on the improved 3D-printed structure adjustment technology, the 3D microbridge humidity sensors and 3D micropillar capacitor electrodes can be fabricated with high repeatability and efficiency. The 3D-printed microscale devices' efficiencies in this study are superior to most previously reported microscale devices, with their efficiencies adjustable by the relative humidity during the printing process. Furthermore, the 3D-printed humidity sensor is demonstrated to be used as a contactless finger sensor, which shows potential application in preventing disease cross-infection in public facilities. Improveme

关键词： Meniscus-guided 3D printing Capillary replenishment flow Evaporation Nanoparticle deposition Micro humidity sensor Micro capacitor

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