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Fluid Dynamics & Materials Processing 2024年第6期20卷 1425-1439页

作者： Ivan Sboev Tatyana Lyubimova Konstantin Rybkin Michael Kuchinskiy UEC-Aviadvigatel 93 Komsomolsky ProspectPerm614990Russia laboratory of Computing hydrodynamic Institute of Continuous Media Mechanics UB RASPerm614013Russia laboratory of interfacial hydrodynamic Perm State UniversityPerm614068Russia

The intensification of physicochemical processes in the sonochemical reactor chamber is widely used in problems of synthesis,extraction and *** of the most important mechanisms at play in such processes is the acoustic cavitation due to the non-uniform distribution of acoustic pressure in the *** has a strong impact on the surface degradation *** this work,a numerical calculation of the acoustic pressure distribution inside the reactor chamber was performed using COMSOL *** numerical results have revealed the dependence of the structure of the acoustic pressure field on the boundary conditions for various thicknesses of the piezoelectric *** particular,the amplitude of the acoustic pressure is minimal in the case of absorbing boundaries,and the attenuation becomes more significant as the thickness of the piezoelectric transducer *** addition,reflective boundaries play a significant role in the formation and distribution of zones of maximum cavitation activity.

关键词： Ultrasound numerical simulation acoustic pressure field cavitation erosion foil test

The mechanism of dentine hypersensitivity:Stimuli-induced directional cation transport through dentinal tubules

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Nano Research 2023年第1期16卷 991-998页

作者： Nuo Chen Jingjing Deng Shengjie Jiang Xiang-Yu Kong Teng Zhou Kai Zhao Zuohui Xiao Huimin Zheng Weipeng Chen Congcong Zhu Xinyu Liu Liping Wen Yan Wei Xuliang Deng Lei Jiang Beijing laboratory of Biomedical Materials Department of Geriatric DentistryPeking University School and Hospital of StomatologyBeijing 100081China Central laboratory Peking University School and Hospital of StomatologyBeijing 100081China CAS Key laboratory of Bio-inspired Materials and interfacial Science Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China Mechanical and Electrical Engineering College Hainan UniversityHainan 570228China School of Future Technology University of Chinese Academy of Sciences Beijing 100049China

Dentine hypersensitivity is an annoying worldwide disease,yet its mechanism remains *** long-used hydrodynamic theory,a stimuli-induced fluid-flow process,describes the pain ***,no experimental evidence supports the ***,we demonstrate that stimuli-induced directional cation transport,rather than fluid-flow,through dentinal tubules actually leads to dentine *** in vitro/in vivo electro-chemical and electro-neurophysiological approaches reveal the cation current through the nanoconfined negatively charged dentinal tubules coming from external stimuli(pressure,pH,and temperature)on dentin surface and further triggering the nerve impulses causing the dentine ***,the cationic-hydrogels blocked dentinal tubules could significantly reduce the stimuli-triggered nerve action potentials and the anionhydrogels counterpart enhances those,supporting the cation-flow transducing dentine ***,the inspired ion-blocking desensitizing therapies have achieved remarkable pain relief in clinical *** proposed mechanism would enrich the basic knowledge of dentistry and further foster breakthrough initiatives in hypersensitivity mitigation and cure.

关键词： dentine hypersensitivity cation transport dentinal tubules Ionic-current-rectification

A dynamic rheological model for thin-film lubrication

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Chinese Physics B 2013年第1期22卷 426-433页

作者：张向军黄颖郭岩宝田煜孟永钢 State Key laboratory of Tribology Tsinghua University

In this study, the effects of the non-Newtonian rheological properties of the lubricant in a thin-film lubrication regime between smooth surfaces were investigated. The thin-film lubrication regime typically appears in Stribeck curves with a clearly observable minimum coefficient of friction （COF） and a low-COF region, which is desired for its lower energy dissipation. A dynamic rheology of the lubricant from the hydrodynamic lubrication regime to the thin-film lubrication regime was proposed based on the convected Maxwell constitutive equation. This rheology model includes the increased relaxation time and the yield stress of the confined lubricant thin film, as well as their dependences on the lubricant film thickness. The Deborah number （De number） was adopted to describe the liquid-solid transition of the confined lubricant thin film under shearing. Then a series of Stribeck curves were calculated based on Tichy＇s extended lubrication equations with a perturbation of the De number. The results show that the minimum COF points in the Stribeck curve correspond to a critical De number of 1.0, indicating a liquid-to-solid transition of the confined lubricant film. Furthermore, the two proposed parameters in the dynamic rheological model, namely negative slipping length b （indicating the lubricant interracial effect） and the characteristic relaxation time λ0, were found to determine the minimum COF and the width of the low-COF region, both of which were required to optimize the shape of the Stribeck curve. The developed dynamic theological model interprets the correlation between the rheological and interfacial properties of lubricant and its lubrication behavior in the thin-film regime.

关键词： rheology viscoelasticity Deborah number thin-film lubrication

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Orientation-dependent hydrodynamic Instabilities from Chemo-Marangoni Cells to Large Scale interfacial Deformations

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Chinese Journal of Chemical Engineering 2007年第5期15卷 748-753页

作者：石英 Kerstin Eckert State Key laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an 710049 China Institute for Aerospace Engineering Technische Universitat Dresden D-01062 Dresden Germany

The interplay between chemistry and interfacial-tension-driven hydrodynamic instabilities has been studied experimentally. The system on hand consists of two immiscible liquids separated along an initially plane interface at which an interfacial reaction takes place to produce in situ a surfactant. It is identified that the dynamics of the system depends on the orientation of the Hele-Shaw cell with respect to the vector of gravity. If the nele-Shaw cell is placed vertically, Marangoni cells with vigorous convection develop in both phases along a nearly planar interface. However, if the Hele-Shaw cell is tilted off the gravity, the instabilities in the system are characterized by the large scale interracial deformation with a spatio-temporal periodicity together with the chemo-Marangoni convection. The focus is on the exploration of the transition from the cellular mode to the large scale interfacial deformation.

关键词： interfacial reaction in situ produced surfactant Marangoni convection interfacial deformation

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Metal-soil interface adhesion in clay clogging during shield tunneling:Theoretical model and experimental validation

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Underground Space 2024年第2期15卷 188-202页

作者： Yong Fang Bin Zhuo Yubo Wang Hu Luo Junfeng Sun Yuxiang Yao Key laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China

Clogging is a major geohazards risk in mechanized tunnelling through cohesive *** clogging results from the high adhesion between the clay and *** on the water film theory and Reynolds fluid equation,the interfacial adhesion between metal and soil is simplified in this study as viscous hydrodynamic behavior between *** the influence of capillary force and the viscous force of water film at the interface between metal and soil,a theoretical calculation model of interfacial adhesion between metal and soil is *** influence of water film thickness and separation rate on the interfacial adhesion between metal and soil is qualitatively ***,the adhesion stress between the clay and the metal surface was tested with a pullout test and the influence of moisture content,pullout rates and types of clay minerals on the adhesion stress was ***,the calculation model of adhesion force was compared with the experimental *** calculation model of soil adhesion stress established in this paper can quantitatively describe the relationship between soil adhesion force and moisture content and can also qualitatively reveal the influence mechanism of soil moisture content on adhesion stress.

关键词： EPB clogging Adhesion stress Mechanics model Clays Mechanism analysis Experimental test

Stability of stratified flow and slugging in horizontal gas-liquid flow

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Progress in Natural Science:Materials International 2005年第11期15卷 1026-1034页

作者： GU Hanyang and GUO Liejin (State Key laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China) State Key laboratory of Multiphase Flow in Power Engineering Xi''an Jiaotong University Xi''an 710049 China

A transient one-dimensional two-fluid model is proposed to investigate numerically the interfacial instability and the onset of slugging for liquid-gas flow in a horizontal duct. In the present model, the effects of surface tension and transverse variations in dynamic pressure are taken into account. The evolution of interfacial disturbances is displayed and compared with the linear viscous Kelvin-Helmholtz stability analyses. It shows that interfacial wave is more instable due to the non-linear effect. The model predicts well the stability limit of stratified flow in comparison with the experimental data, and also automatically tracks the onset of slugging. The results show that the initiation of hydrodynamic slugging is related to local interfacial instability. Based on the cycle of slugging, a model for slug frequency is presented, which predicts the trends of slug frequencies with gas/liquid flow rate well in comparison with the available data. The effects of physical properties on slugging have been examined. It is found that with the increase in the gas viscosity and liquid density the slugging would be inhibited, whereas, with the increase in liquid viscosity and gas density, the slugging can be promoted.

关键词： two-fluid model Kelvin-Helmholtz stability interfacial instability onset of slugging gas-liquid stratified flow.

Insights into friction behavior of textured amorphous carbon and lubricant composite system: Dependence on the lubricant viscosity and textured shape

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Progress in Natural Science:Materials International 2023年第5期33卷 616-624页

作者： Jiaqing Ding Naizhou Du Xubing Wei Xiaowei Li Zan Chen Shiqi Lu Haolin Zhang Cunao Feng Kai Chen Jianghao Qiao Dekun Zhang Kwang-Ryeol Lee School of Materials Science and Physics China University of Mining and Technology Key laboratory of Marine Materials and Related Technologies Zhejiang Key Laboratory of Marine Materials and Protective Technologies Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Computational Science Center Korea Institute of Science and Technology

Combining textured amorphous carbon(a-C) film with lubricant achieves ultra-low friction to improve the mechanical component’s service life. However, the coupling influence of lubricant viscosity and textured shape on friction behavior and interfacial transformation are still unclear. In this work, the evolution of friction performance with Poly-alpha-olefin viscosities and its dependence on textured shapes were investigated by reactive molecular dynamics simulation. Results reveal that as the textured shape is fixed, increasing the lubricant viscosity causes friction coefficient to decline first and then increase, due to the hydrodynamic lubrication and regional aggregation of lubricant. While under same lubricant condition, rectangular textured systems exhibit lower friction coefficient than circular textured ones, attributing to the formation of stable lubricant film without serious aggregation.

关键词： Amorphous carbon Surface texture Lubricant Reactive molecular dynamics

On the boundary slip of fluid flow

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Science China(Physics,Mechanics & Astronomy) 2005年第2期48卷 178-187页

作者： WU Chengwei MA Guojun State Key laboratory of Structural Analysis for Industrial Equipment Department of Engineering Mechanics Dalian University of Technology Dalian 116024 China State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering Mechanics Dalian University of Technology Dalian 116024 China

This paper presents a stress controlled boundary slip model and predicts the fluid-solid interface slip in a system of parallel sliding plates or a sphere approaching a smooth plane. The numerical simulation results are in striking agreement with the existing experimental observations. This model assumes that there is a limiting shear stress. No slip occurs if the surface shear stress is smaller than the limiting shear stress, and slip occurs when the surface shear stress equals it. It is found that boundary slip dramatically decreases the hydrodynamic pressure if the two squeezed surfaces have the same slip property. Finally, the hydrodynamic force reaches a saturation status and almost does not decrease any more. Compared with the no-slip solution, hydrodynamic force is found to decrease by over two orders in the case of boundary slip. When the squeezed surfaces have different slip properties, however, the hydrodynamic pressure is mainly controlled by the surface having a smaller surface limiting shear stress, and reduces more slowly compared with the case of two surfaces having the same slip property. Even when one of the surfaces has a zero surface limiting shear stress, a considerable hydrodynamic force still exists.

关键词： boundary slip, interfacial limiting shear stress, fluid flow.

interfacial friction at action: Interactions, regulation, and applications

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Friction 2023年第12期11卷 2153-2180页

作者： Zhiran YI Xiong WANG Wanbo LI Xuezhi QIN Yang LI Kaiqiang WANG Yunting GUO Xing LI Wenming ZHANG Zuankai WANG Department of Mechanical Engineering City University of Hong KongHong Kong 999077China Hong Kong Centre for Cerebro–caradiovasular Health Engineering(COCHE) Hong Kong 999077China State Key laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China Key laboratory of Bionic Engineering Ministry of EducationJilin UniversityChangchun 130022China

Friction is a fundamental force that impacts almost all interface-related *** the past decade,there is a revival in our basic understanding and practical applications of the *** this review,we discuss the recent progress on solid–liquid interfacial friction from the perspective of *** first discuss the fundamentals and theoretical evolution of solid–liquid interfacial friction based on both bulk interactions and molecular ***,we summarize the interfacial friction regulation strategies manifested in both natural surfaces and artificial systems,focusing on how liquid,solid,gas,and hydrodynamic coupling actions mediate interfacial ***,we discuss some practical applications that are inhibited or reinforced by interfacial *** last,we present the challenges to further understand and regulate interfacial friction.

关键词： interfacial friction solid-liquid interface interfacial interaction friction regulation

Numerical simulation of the hydrodynamic instability experiments and flow mixing

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Science China(Physics,Mechanics & Astronomy) 2009年第12期52卷 2027-2040页

作者： BAI JingSong WANG Tao LI Ping ZOU LiYong LIU CangLi National Key laboratory for Shock Wave and Detonation Physics Research Institute of Fluid PhysicsCAEPMianyang 621900China

Based on the numerical methods of volume of fluid (VOF) and piecewise parabolic method (PPM) and parallel circumstance of Message Passing Interface (MPI),a parallel multi-viscosity-fluid hydrodynamic code MVPPM (Multi-Viscosity-Fluid Piecewise Parabolic Method) is developed and performed to study the hydrodynamic instability and flow mixing. Firstly,the MVPPM code is verified and validated by simulating three instability cases:The first one is a Riemann problem of viscous flow on the shock tube; the second one is the hydrodynamic instability and mixing of gaseous flows under re-shocks; the third one is a half height experiment of interfacial instability,which is conducted on the AWE's shock tube. By comparing the numerical results with experimental data,good agreement is achieved. Then the MVPPM code is applied to simulate the two cases of the interfacial instabilities of jelly models acceler-ated by explosion products of a gaseous explosive mixture (GEM),which are adopted in our experi-ments. The first is implosive dynamic interfacial instability of cylindrical symmetry and mixing. The evolving process of inner and outer interfaces,and the late distribution of mixing mass caused by Rayleigh-Taylor (RT) instability in the center of different radius are given. The second is jelly layer ex-periment which is initialized with one periodic perturbation with different amplitude and wave length. It reveals the complex processes of evolution of interface,and presents the displacement of front face of jelly layer,bubble head and top of spike relative to initial equilibrium position vs. time. The numerical results are in excellent agreement with that experimental images,and show that the amplitude of initial perturbations affects the evolvement of fluid mixing zone (FMZ) growth rate extremely,especially at late times.

关键词： interfacial instability flow mixing multi-fluid hydrodynamic fluid mixing zone

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