微纳系统中粒子-流体输运机制及热质传递规律研究

This project focuses on common crucial scientific issues of particle-fluid transport in micro/nano system: (1) The quantitative mechanism of two-way coupling interaction between particle and gas in micro scale will be explored; the micro-scale dynamic model of particle-gas two-phase flow using partitioned simulation and interface coupling method will be constructed; the law of coupled convection-radiation heat transfer of particle-gas two-phase flow in microchannel will be revealed; the theory on flow and heat transfer of particle-gas two-phase fluid in micro scale will be established. (2) The dynamical behavior of particles in liquid microfluid will be investigated; the three dimensional distribution model for particle concentration and diameter along the whole flow path in microchannel will be constructed; a new explanation of the enhanced/weakened heat transfer nature and mechanism for nanofluid in micro system will be obtained based on the analysis of the equivalent properties of particle-liquid fluid and wall characteristics; the theory on heat and mass transfer of micro particle-liquid flow under the coupling effect of flow and magnetic fields will be developed. (3) The mechanism and quantitative rules for the ultrafast transport of fluid and particles through nanochannel will be explored at the molecular level; the mechanism for selective transport of nanoparticles through nanochannel will be revealed based on the multi-level analysis of energy barrier, effective size of nanoparticle, and Debye length; the widely applicable criterion and principle for the selective transport will be proposed. Based on the above research, the theoretical system for particle-fluid multiphase flow and heat mass transfer in micro/nano scale will be established. It can lead the development of advanced micro/nano fluidic systems, and thus is of significant scientific and engineering value.

本项目拟围绕微纳系统粒子-流体输运中共性关键科学问题开展深入系统研究，包括：1）揭示微尺度气体与粒子双向耦合作用量化规律，构建分区模拟-界面耦合的微尺度气固两相流体动力学数理模型，探索微通道气固两相对流-辐射耦合传热机制，建立微尺度粒子-气体两相流动与传热理论；2）探究液相微流体中粒子动力学行为规律，构建微通道粒子浓度、粒径全流程三维空间分布模型，从粒子-液体等效物性及壁面属性出发全新诠释纳米流体强化/弱化微系统传热的本质及机理，发展基于磁场/流场耦合作用的微尺度液固两相热质输运理论；3）从分子层面揭示纳米通道内流体/粒子高通量输运机理及量化规律，基于能量势垒强度、粒子有效尺寸、Debye长度分析，多层面揭示纳米通道对纳米粒子的选择性输运机制，提出具广泛适用性的选择性输运判据及准则。上述研究有望构建微纳尺度粒子-流体多相流与传热传质理论体系，指导先进微纳流系统开发，具有重要科学及工程意义。

微纳系统粒子多相流在微流控芯片、微能源系统等领域都有重要应用。本项目基于介微观数值模拟和实验方法，对微系统中气粒输运机制及热质传递规律、液粒输运机制及热质传递规律、纳米通道内受限流体及其内部粒子输运机制开展了研究，取得以下主要成果：(1)构建了微尺度滑移流曲边界新格式，通过引入克努森数Kn对气固边界条件及松弛时间进行修正，建立了可实现非连续条件下气-粒间双向耦合作用的微尺度气固两相全尺寸多松弛格子Boltzmann方法，揭示了微通道气相流场中颗粒动力学行为及迁移规律，探索了界面速度滑移和温度跳跃非连续效应下的气-粒间流动阻力及传热规律，提出了首个考虑Kn数、Re数、颗粒温度影响的微尺度气-粒两相间拖曳力系数和Nu数准则方程；构建了微尺度气体-近壁颗粒对流-远/近场辐射耦合传热模型，定量揭示了近壁颗粒对流辐射耦合传热规律。(2)基于Micro-PIV/PTV实验和浸没边界-格子Boltzmann耦合数值模型构建，揭示了微通道液体流场中颗粒的有序化迁移机制及径向分布规律，探索了椭球形颗粒不同运动模态及其作用力机制，发现颗粒及颗粒链周围的微流场结构演变规律，提出了基于自由摆动方柱扰流作用的微尺度液固两相高效热质传递理论和方法。(3)基于MD研究，发现了纳米通道内水的结构转变及其对输运特性的影响，揭示了温差驱动下纳米通道内有序化结构水的超速输运现象(即喷泉效应)，分析了压差作用下纳米通道高通量输运的主导势垒，探究了纳米通道内水中蛋白质粒子输运特性及高效输运机理，揭示了壁面亲疏水性、带电特性、电解质溶液对蛋白质粒子过孔输运的影响机制及作用规律，提出了基于温度调控的纳米通道内水-质子的高通量选择性输运机制及方法。项目发表论文100篇(SCI收录47篇、EI收录69篇)；申请专利3项；指导毕业博士生6人、硕士生10人；获教育部自然科学一等奖1项、入选Elsevier中国高被引学者1人。