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A Variational Model for Two-Phase Immiscible Electroosmotic Flow at Solid Surfaces

Communications in Computational Physics 2012年第3期11卷 831-862页

作者： Sihong Shao tiezheng qian Joint KAUST-HKUST Micro/Nanofluidics Laboratory Hong Kong University of Science and TechnologyClear Water BayHong KongLMAMand School ofMathematical SciencesPeking UniversityBeijing 100871China Department of Mathematics and Joint KAUST-HKUST Micro/Nanofluidics Laboratory Hong Kong University of Science and TechnologyClear Water BayHong Kong

We develop a continuum hydrodynamic model for two-phase immiscible flows that involve electroosmotic effect in an electrolyte and moving contact line at solid *** model is derived through a variational approach based on the Onsager principle of minimum energy *** approach was first presented in the derivation of a continuum hydrodynamic model for moving contact line in neutral two-phase immiscible flows(qian,Wang,and Sheng,*** Mech.564,333-360(2006)).Physically,the electroosmotic effect can be formulated by the Onsager principle as well in the linear response ***,the same variational approach is applied here to the derivation of the continuum hydrodynamic model for charged two-phase immiscible flows where one fluid component is an electrolyte exhibiting electroosmotic effect on a charged surface.A phase field is employed to model the diffuse interface between two immiscible fluid components,one being the electrolyte and the other a nonconductive fluid,both allowed to slip at solid *** model consists of the incompressible Navier-Stokes equation for momentum transport,the Nernst-Planck equation for ion transport,the Cahn-Hilliard phase-field equation for interface motion,and the Poisson equation for electric potential,along with all the necessary boundary *** particular,all the dynamic boundary conditions at solid surfaces,including the generalized Navier boundary condition for slip,are derived together with the equations of motion in the bulk *** examples in two-dimensional space,which involve overlapped electric double layer fields,have been presented to demonstrate the validity and applicability of the model,and a few salient features of the two-phase immiscible electroosmotic flows at solid *** wall slip in the vicinity ofmoving contact line and the Smoluchowski slip in the electric double layer are both investigated.

关键词： Electroosmotic flow moving contact line slip boundary condition

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Study of Mechanical Aharonov-Anandan Phase

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Chinese Physics Letters 1991年第2期8卷 59-62页

作者： XU Jingbo qian tiezheng GAO Xiaochun Department of Physics Zhejiang UniversityHangzhou 310027

Some examples of a new kind of the Aharonov-Anandan phase which is of mechanical origin are *** is the non-adiabatic generalization of the mechanical Berry *** first study the periodic motion and then the interference... 详细信息

关键词： phase. effect. Berry

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Stick-Slip Motion of Moving Contact Line on Chemically Patterned Surfaces

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Communications in Computational Physics 2010年第3期7卷 403-422页

作者： Congmin Wu Siulong Lei tiezheng qian Xiaoping Wang Department of Mathematics Hong Kong University of Science and TechnologyClear Water BayKowloonHong Kong Department of Mathematics and Joint KAUST-HKUST Micro/Nano-Fluidics Laboratory Hong Kong University of Science and TechnologyClear Water BayKowloonHong Kong

Based on our continuum hydrodynamic model for immiscible two-phaseflows at solid surfaces, the stick-slip motion has been predicted for moving contactline at chemically patterned surfaces [Wang et al., J. Fluid Mech., 605 (2008), pp. 59-78].In this paper we show that the continuum predictions can be quantitatively verifiedby molecular dynamics (MD) simulations. Our MD simulations are carried out fortwo immiscible Lennard-Jones fluids confined by two planar solid walls in Poiseuilleflow geometry. In particular, one solid surface is chemically patterned with alternating stripes. For comparison, the continuum model is numerically solved using material parameters directly measured in MD simulations. From oscillatory fluid-fluidinterface to intermittent stick-slip motion of moving contact line, we have quantitativeagreement between the continuum and MD results. This agreement is attributed tothe accurate description down to molecular scale by the generalized Navier boundary condition in our continuum model. Numerical results are also presented for therelaxational dynamics of fluid-fluid interface, in agreement with a theoretical analysisbased on the Onsager principle of minimum energy dissipation.

关键词： Moving contact line slip boundary condition patterned surface

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Molecular Hydrodynamics of the Moving Contact Line in Two-Phase Immiscible Flows

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Communications in Computational Physics 2006年第1期1卷 1-52页

作者： tiezheng qian Xiao-Ping Wang Ping Sheng Department of Mathematics The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina Department of Physics The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina

The no-slip boundary condition,i.e.,zero fluid velocity relative to the solid at the fluid-solid interface,has been very successful in describing many macroscopic flows.A problem of principle arises when the no-slip boundary condition is used to model the hydrodynamics of immiscible-fluid displacement in the vicinity of the moving contact line,where the interface separating two immiscible fluids intersects the solid *** ago it was already known that the moving contact line is incompatible with the no-slip boundary condition,since the latter would imply infinite dissipation due to a non-integrable singularity in the stress near the contact *** this paper we first present an introductory review of the *** then present a detailed review of our recent results on the contact-line motion in immiscible two-phase flow,from molecular dynamics(MD)simulations to continuum hydrodynamics *** extensive MD studies and detailed analysis,we have uncovered the slip boundary condition governing the moving contact line,denoted the generalized Navier boundary *** have used this discovery to formulate a continuum hydrodynamic model whose predictions are in remarkable quantitative agreement with the MD simulation results down to the molecular *** results serve to affirm the validity of the generalized Navier boundary condition,as well as to open up the possibility of continuum hydrodynamic calculations of immiscible flows that are physically meaningful at the molecular level.

关键词： Moving contact line slip boundary condition molecular dynamics continuum hydrodynamics

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Active Brownian particles simulated in molecular dynamics

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Chinese Physics B 2020年第9期29卷 222-232页

作者： Liya Wang Xinpeng Xu Zhigang Li tiezheng qian Faulty of Civil Engineering and Mechanics Jiangsu UniversityZhenjiang 212013China Faculty of Physics Guangdong-Technion-Israel Institute of TechnologyShantou 515063China Department of Mechanical and Aerospace Engineering Hong Kong University of Science and TechnologyHong KongChina Department of Mathematics Hong Kong University of Science and TechnologyHong KongChina

In the numerical studies of active particles, models consisting of a solid body and a fluid body have been well established and widely used. In this work, such an active Brownian particle (ABP) is realized in molecular dynamics (MD) simulations. Immersed in a fluid, each ABP consists of a head particle and a spherical phantom region of fluid where the flagellum of a microswimmer takes effect. Quantitative control over the orientational persistence time is achieved via an external stochastic dynamics. This control makes it possible to validate ABP's diffusion property in a wide range of particle activity. In molecular description, the axial velocity of ABP exhibits a Gaussian distribution. Its mean value defines the active velocity which increases with the active force linearly, but shows no dependence on the rotational diffusion coefficient. For the active diffusion coefficient measured in free space, it shows semi-quantitative agreement with the analytical result predicted by a minimal ABP model. Furthermore, the active diffusion coefficient is also calculated by performing a quantitative analysis on the ABP's distribution along x axis in a confinement potential. Comparing the active diffusion coefficients in the above two cases (in free space and in confinement), the validity of the ABP modeling implemented in MD simulations is confirmed. Possible reasons for the small deviation between the two diffusion coefficients are also discussed.

关键词： active Brownian particle diffusion confinement boundary

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Aharonov-Anandan Phase in the Degenerate Parametrie Amplifier

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Chinese Physics Letters 1991年第10期8卷 499-502页

作者： qian tiezheng XU Jingbo GAO Xiaochun Department of Physics Zhejiang UniversityHangzhou 310027

As a non-adiabatic generalization of a recent work of Gerry,the manifestation of the Aharonov-Anajidan phase in the degenerate parametric amplifier of quantum optics is discussed by making use of the Lewis-Riesenfeld quantum *** find the Lewis invariant for the system and study its *** Aharonov-Anandan phase is then calculated and the connection between the Aharonov-Anandan phase difference and the average photon-number of the output field is ***,the observable effect of the phase difference is investigated.

关键词： theory quantum phase

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Molecular hydrodynamics of the moving contact line

Molecular hydrodynamics of the moving contact line

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2006"与统计有关的凝聚态物理中一些数值计算问题"研讨会

作者： tiezheng qian Mathematics Department Hong Kong University of Science and Technology

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新型显示薄膜喷墨打印技术的数学建模与分析

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中国科学：数学 2024年第3期54卷 377-406页

作者：丁时进辛周平王筱平钱铁铮李进开徐新鹏华南师范大学数学科学学院广州510631 香港中文大学数学科学研究所中国香港香港科技大学数学系中国香港香港中文大学(深圳)理工学院深圳518172 深圳市大数据研究院深圳518172 广东以色列理工学院物理系汕头515063

本文将新型显示薄膜喷墨打印技术的关键工艺过程“喷墨打印-干燥/烘烤成膜”中多组分聚合物溶液在压电作用下从喷管内喷出均匀液滴、液滴在基板上着床并融合成均匀的液体薄膜、液体薄膜经过蒸发留下溶质(如有机发光二极管OLED(organic l... 详细信息

本文将新型显示薄膜喷墨打印技术的关键工艺过程“喷墨打印-干燥/烘烤成膜”中多组分聚合物溶液在压电作用下从喷管内喷出均匀液滴、液滴在基板上着床并融合成均匀的液体薄膜、液体薄膜经过蒸发留下溶质(如有机发光二极管OLED(organic light-emitting diode))形成均匀显示薄膜的3个核心科学问题,在数学上提炼为多组分聚合物流体带移动接触线和动态接触角以及带有蒸发条件的固-液-气多相耦合的自由界面问题.本文首先对这些问题的Newton流的数学模型进行热力学自洽的系统综述和完善,然后对包含相分离、溶剂蒸发和非Newton黏弹性等多物理现象的同类自由界面问题进行成体系的数学建模,对模型的理论分析和数值模拟提出一些研究思路.本文希望通过解决这些数学问题突破新型显示薄膜喷墨打印工艺的关键技术瓶颈,提高打印的良品率,推进产业化,促进数学在解决国家重大需求难题中的应用.本文以新型显示薄膜喷墨打印技术核心科学问题为背景,给数学工作者提出了一些新的重要的数学问题,同时也为相关材料科学家提供了可行的数学方案,为双方搭起了良好的沟通桥梁.

关键词：非Newton流喷墨打印液滴动力学液体薄膜蒸发移动接触线和动态接触角自由界面问题

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Interannual variability of boreal summer intraseasonal oscillation over the northwestern Pacific influenced by the Pacific Meridional Mode

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Atmospheric and Oceanic Science Letters 2025年第1期18卷 6-11页

作者： Haoyu Zhou Pang-Chi Hsu Lin Chen Yitian qian Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environmental Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science and TechnologyNanjingChina

During the boreal summer,intraseasonal oscillations exhibit significant interannual variations in intensity over two key regions:the central-western equatorial Pacific(5°S-5°N,150°E-150°W)and the subtropical Northwestern Pacific(10°-20°N,130°E-175°W).The former is well-documented and considered to be influenced by the ENSO,while the latter has received comparatively less attention and is likely influenced by the Pacific Meridional Mode(PMM),as suggested by partial correlation analysis *** elucidate the physical processes responsible for the enhanced(weakened)intraseasonal convection over the subtropical northwestern Pacific during warm(cold)PMM years,the authors employed a moisture budget *** findings reveal that during warm PMM years,there is an increase in summer-mean moisture over the subtropical northwestern *** increase interacts with intensified vertical motion perturbations in the region,leading to greater vertical moisture advection in the lower troposphere and consequently resulting in convective *** a process is pivotal in amplifying intraseasonal convection *** observational findings were further verified by model experiments forced by PMM-like sea surface temperature patterns.

关键词： Boreal summer intraseasonal oscillation Interannual variability Pacific Meridional Mode Moisture budget analysis

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Recent advances in exploring new blood-based biomarkers for the early diagnosis of gastric cancer

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Science China Chemistry 2025年第1期 35-45页

作者： Xinyu Peng qian Ma Da Han School of Life Science Shanghai University Institute of Molecular Medicine Shanghai Key Laboratory for Nucleic Acid Chemistry and Nanomedicine State Key Laboratory of Oncogenes and Related Genes Renji Hospital School of Medicine Shanghai Jiao Tong University Department of Research and Development Intellinosis Biotechnologies Co.Ltd.

Gastric cancer(GC) is a prevalent and lethal malignancy worldwide, and the 5-year survival rate is less than 30%. The absence of distinctive symptoms often leads to late-stage diagnosis, contributing to a grim prognosis. Early detection is pivotal for improving the survival rates and outcomes of GC patients. Traditional diagnostic methods, including gastroscopy and histopathological examination, are restricted in the early diagnosis of GC. Conventional protein biomarkers, such as carcinoembryonic antigen(CEA), carbohydrate antigen 19-9(CA19-9), and carbohydrate antigen 72-4(CA72-4), exhibit insufficient sensitivity and specificity for GC screening, which diminishes their clinical value. Recently, novel circulating biomarkers, such as circulating tumor cells(CTCs), circulating tumor cell DNA(ct DNA), and circulating free RNA(cf RNA), have emerged as promising candidates in the burgeoning field of liquid biopsy due to their superior sensitivity and specificity. This review focuses on the latest research on blood-based biomarkers for GC diagnosis and examines the clinical potentials and challenges associated with these emerging biomarkers.

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