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Less turbulent flow can transport more heat in thermal convection

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Less turbulent flow can transport more heat in thermal conve...

中国力学大会-2015

作者： chong kai-leong Kaczorowski Matthias Huang Shi-Di Xia Ke-Qing 香港中文大学物理系

The effects of geometrical confinement on turbulent Rayleigh-Benard convection are investigated using direct numerical simulations(DNS).We find surprisingly the significant enhancement in heat transport efficiency(in terms of Nusselt numer Nu)under confinement with the reduction in turbulent intensity,where they were widely believed to be ***

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不同形状液滴撞击固壁的动力学特性研究

中国科学：物理学、力学、天文学 2024年第10期54卷 68-78页

作者：李阳庄启亮王伯福上海市应用数学和力学研究所上海市能源工程力学重点实验室上海大学力学与工程科学学院上海200444

液滴撞击壁面广泛存在于喷墨打印、喷涂、叶轮机械等工业应用中,相关研究具有重要的科学和应用价值.本文采用数值模拟方法研究了不同形状液滴撞击亲水/超疏水壁面的动力学特性.研究表明,液滴撞击亲水壁面时,不同的初始形状条件下液滴撞... 详细信息

液滴撞击壁面广泛存在于喷墨打印、喷涂、叶轮机械等工业应用中,相关研究具有重要的科学和应用价值.本文采用数值模拟方法研究了不同形状液滴撞击亲水/超疏水壁面的动力学特性.研究表明,液滴撞击亲水壁面时,不同的初始形状条件下液滴撞击后都经历了铺展过程,形状的不同致使在壁面上的液滴边缘处形成的颈部射流形状有所差异,铺展过程后半阶段与初始形状无关.液滴撞击超疏水壁面时,不同初始形状和不同韦伯数(We)情况下,液滴在冲击过程中都经历铺展-回缩-反弹的形态变化;液滴对壁面形成的冲击力演化均有两个明显的峰值,这两个峰值分别由液滴的惯性冲击和液滴回缩阶段中形成的沃辛顿射流产生;不同韦伯数(We)情况下,相同形状的液滴冲击力演化规律一致;相同韦伯数(We)情况下,液滴形状越扁平,惯性冲击力峰值也越大,且达到峰值的时间越短.

关键词：液滴撞击壁面形状动力学

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基于超分辨率重构方法的湍流流场重构

实验流体力学 2022年第3期36卷 102-109页

作者：江昊王伯福庄启亮卢志明上海大学力学与工程科学学院上海市应用数学和力学研究所上海200072 上海市力学信息学前沿科学研究基地上海200072

从低分辨率流场数据中获取精细流场信息具有重要的研究意义。基于卷积神经网络的超分辨率重构方法是近年来发展的一种较为有效的精细流场重构方法。本文采用高效亚像素卷积神经网络(Efficient Sub-Pixel Convolutional Neural Network,E... 详细信息

从低分辨率流场数据中获取精细流场信息具有重要的研究意义。基于卷积神经网络的超分辨率重构方法是近年来发展的一种较为有效的精细流场重构方法。本文采用高效亚像素卷积神经网络(Efficient Sub-Pixel Convolutional Neural Network,ESPCN),对Rayleigh–Bénard(RB)对流的数值模拟数据和湍流边界层(Turbulent Boundary Layer,TBL)的实验测量数据进行了超分辨率重构,并与双三次插值方法(Bicubic Interpolation)的重构结果进行对比。对比结果表明:在较小的下采样比下,ESPCN方法和Bicubic方法的重构精度相当;在较大的下采样比下,ESPCN方法的重构精度明显优于Bicubic方法。此外,ESPCN方法对数据梯度较大区域的超分辨率重构效果优于Bicubic方法。

关键词：超分辨率重构方法湍流卷积神经网络流场重构

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湍流热对流调制及其机理的研究现状和展望

空气动力学学报 2022年第2期40卷 156-164,173,146,I0003页

作者：赵超本庄启亮王伯福吴建钊周全上海大学力学与工程科学学院上海市应用数学和力学研究所上海200072

湍流热对流现象广泛存在于自然界和实际工程应用中,Rayleigh-Bénard(RB)系统是研究湍流热对流问题的经典模型。湍流传热的调制及其机理问题是湍流研究的重点。在经典RB系统中,上下板附近的温度边界层与系统传热关系密切,边界层内热湍... 详细信息

湍流热对流现象广泛存在于自然界和实际工程应用中,Rayleigh-Bénard(RB)系统是研究湍流热对流问题的经典模型。湍流传热的调制及其机理问题是湍流研究的重点。在经典RB系统中,上下板附近的温度边界层与系统传热关系密切,边界层内热湍流结构(羽流)的生成演化特性直接决定着系统传热效率。目前的调制策略主要通过改变上下板边界的几何型形状或改变温度边界条件来控制RB系统的对流强度,实现增强或抑制系统传热。本文主要从边界几何调制、边界温度时间调制和边界温度空间调制三个方面分别介绍和讨论了近年来有关湍流热对流调制及其机理研究方面的最新进展,并在最后提出了针对该方向的一些思考和展望。

关键词：湍流热对流边界层传热湍流调制 Rayleigh-Bénard

Large-eddy simulation of turbulent boundary layer flow over multiple hills

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Journal of Hydrodynamics 2023年第4期35卷 746-756页

作者： Ying Deng kai leong chong Yan Li Zhi-ming Lu Bo-fu Wang Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai200072China School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai200092China

Atmospheric boundary layer(ABL)flow over multiple-hill terrain is studied *** spectral vanishing viscosity(SVV)method is employed for implicit large eddy simulation(ILES).ABL flow over one hill,double hills,and three hills are presented in *** instantaneous three-dimensional vortex structures,mean velocity,and turbulence intensity in mainstream and vertical directions around the hills are investigated to reveal the main properties of this turbulent *** the flow evolution downstream,the Kelvin-Helmholtz vortex,braid vortex,and hairpin vortex are observed *** turbulence intensity is enhanced around crests and reduced in the recirculation *** present results are helpful for understanding the impact of topography on the turbulent *** findings can be useful in various fields,such as wind energy,air pollution,and weather forecasting.

关键词： Large-eddy simulation(LES) atmospheric boundary layer(ABL)flow complex terrain turbulent flow fields

Viral inactivation by irradiation rays

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Light(Science & Applications) 2023年第4期12卷 505-506页

作者： kai-kai Liu chong-Xin Shan Henan Key Laboratory of Diamond Optoelectronic Materials and Devices School of Physics and MicroelectronicsZhengzhou UniversityZhengzhouChina

Viral infection can lead to serious illness and death around the world,as exemplified by the spread of *** irradiation rays can inactive virions through ionizing and non-ionizing *** application of light in viral inactivation and the underlying mechanisms are reviewed by the research group of Dayong Jin from University of Technology Sydney.

关键词： effect. inactivation death

Key Parameters Analysis and Regulation of Singlet Oxygen Quenching Rate of Carotenoids

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Chinese Journal of Structural Chemistry 2020年第7期39卷 1226-1234页

作者： ZHAO kai JIANG Wei MENG chong Education Academy Beijing Sport UniversityBeijing 100084China School of Environment Beijing Normal UniversityBeijing 100875China

28 kinds of carotenoids are studied to reveal the key parameters and regulation on the singlet oxygen quenching ***,the quantum chemistry parameters of carotenoids calculated by Gaussian software combined with substitution parameters were used to construct the quantitative structure-activity relationship model(QSAR)of the singlet oxygen quenching rate of *** key parameters affecting the antioxidant activity of carotenoids are revealed,and the data predicted via the QSAR model were provided for subsequent ***,a three-dimensional(3D)pharmacophore model was used to regulate and modify the antioxidant activity of *** correlation coefficients of the modeling group(R2)and verification group(Rpre2)of the established QSAR model were 0.945 and 0.916,respectively,which can be used for the analysis of antioxidant activity of carotenoids;the antioxidant activity of carotenoids can be significantly regulated by the number of conjugated C=C bonds,the energy difference between frontier molecular orbitals and the partial Mulliken charge in C1 and theπ···π*excitation energy E(s);the antioxidant activity of carotenoids can be effectively regulated by the hydrogen bond acceptor pharmacophores on both sides of the conjugated C=C bonds and the hydrophobic groups on the conjugated C=C bond;the hydrophobic substituents attached to conjugated C=C bonds can effectively improve the singlet oxygen quenching rate of carotenoids.

关键词： carotenoids singlet oxygen quenching quantitative structure-activity relationship model 3D pharmacophore model parameters analysis

Influence of Zn Addition on Microstructures and Martensitic Transformation in CuZr-based Alloys

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Journal of Iron and Steel Research International 2016年第1期23卷 31-36页

作者： kai-kai SONG Dian-yu WU Feng WAN Xiao-jun BAI chong-de CAO Department of Physics School of ScienceNorthwestern Polytechnical University School of Mechanical Electrical &Information EngineeringShandong University(Weihai)

Compositional dependences on microstructures and martensitic transformation behaviors in（Cu_（0.5）Zr_（0.5））_（100-x）Zn_x（x=1.5,2.5,4.5,7.0,10.0,and 14.0at.%）alloys were *** was found that CuZr martensites were present in the present *** increasing Zn content,the volume fractions of CuZr martensitic crystals and B2 CuZr phase gradually decrease and increase,*** the addition of high Zn contents（i.e.,7.0,10.0,and 14.0at.%）,the matrix proves to be *** analysis results show that the initial martensitic transformation temperature（M_s）decreases from（412±5）K to（329±5）K as the Zn content increases from 1.5at.% to14.0at.%.The values of Msof Cu-Zr-Zn shape memory alloys are inversely proportional to the number and concentrations of valence electrons（i.e.,e_v/a and c_v）,respectively,implying that the martensitic transformation in CuZrZn alloys could be of electronic nature.

关键词： CuZr-based alloy Zn microstructure phase transition rapid solidification

Triggering triplet excitons of carbon nanodots through nanospace domain confinement for multicolor phosphorescence in aqueous solution

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Nano Research 2024年第7期17卷 6534-6543页

作者： Ya-Chuan Liang Qing Cao Yuan Deng Yong Wang kai-kai Liu chong-Xin Shan School of Electronics and Information Zhengzhou University of Light IndustryZhengzhou 450002China Henan Key Laboratory of Diamond Optoelectronic Material and Devices Key Laboratory of Material PhysicsMinistry of EducationSchool of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450001China Academy for Quantum Science and Technology Zhengzhou University of Light IndustryZhengzhou 450002China Institute of Quantum Materials and Physics Henan Academy of SciencesZhengzhou 450046China

Easy non-radiative decay property of long-lived triplet excitons in aqueous solution obstructs their applications in aquatic *** reported phosphorescence phenomena in aqueous solution have excited researchers enormously but achieving full-color water-soluble phosphorescent carbon nanodots(CNDs)is still a challenging ***,full-color phosphorescence of water-soluble CNDs has been demonstrated by triggering their triplet excitons through nanospace domain confinement,and Förster energy resonance transfer is used for further tuning phosphorescence *** phosphorescence spans across most of the visible spectrum,ranging from 400 to 700 *** an aqueous solution,the CNDs exhibits blue,green,and red phosphorescence,lasting for approximately 6,10,and 7 s,***,the phosphorescence quantum yields are 11.85%,8.6%and 3.56%,making them readily discernible to the naked eyes and laying a solid foundation for practical ***,phosphorescence flexible optical display and bioimaging have been demonstrated by using the multicolor CNDs-based nanomaterials,showing distinct superiority for accuracy and complete display and imaging in complex emission background.

关键词： carbon nanodots triplet excitons multicolor aqueous solution