纳米颗粒吸附界面对流场中液滴动力学行为的调控机理

Adsorption of nanoparticles on drop interface can be widely found in nature and it is the fundamental principle of many cutting edge technologies, such as nanofluid flooding for enhanced oil recovery and nanoparticle-stabilised emulsions. Recent studies demonstrate that nanoparticle adsorption makes drops exhibit non-spherical rest shapes and confers interfaces special mechanical properties such as viscoelasticity. As such, we propose that nanoparticle adsorption on drop interfaces can be used to regulate the dynamical behaviors of drops under flow. To this end, it is crucial to study the coupling mechanisms of multiple physical processes including droplet two-phase flow, transport of nanoparticles and deformation of viscoelastic interfaces. In this project, a numerical model, based on the fundamental theory of multiphase flow dynamics and elastic mechanics, is to be developed for droplet two-phase flow with considering the specificities including convection, diffusion and adsorption of nanoparticles and viscoelasticity of drop interfaces. Experiment is also to be performed on deformation and motion of drops in linear shear flow and in microchannels with complex structures. Numerical and experimental approaches are used to systematically study the dynamics of nanoparticle-adsorbed drops under flow. By revealing the effects of interface viscoelasticity and nanoparticle transport and adsorption, the mechanism of regulating drop dynamical behaviors under flow by nanoparticle adsorption on drop interface will be obtained. The study in this proposal will enrich the fundamental theories of drop dynamics in the discipline of multiphase flow thermophysics and provide theoretical support for the development of related technologies such as nanofluid flooding for enhanced oil recovery.

纳米颗粒在液滴界面的吸附广泛存在于自然界，是石油提高采收率纳米驱、纳米颗粒稳定乳液等前沿技术的基本原理。最新研究表明纳米颗粒吸附可使液滴展现非球形平衡态形状，并且导致界面具有粘弹性等特殊力学性质。由此，本项目提出利用纳米颗粒在液滴界面的吸附调控流场中液滴动力学行为的思想，关键基础科学问题是液滴两相流动、纳米颗粒传输、粘弹性界面变形等物理过程的耦合作用机理。本项目将基于多相流动力学、弹性力学等基础理论，发展考虑纳米颗粒对流扩散与吸附、液滴界面粘弹性等特殊性的液滴动力学模拟方法，结合剪切流场和复杂结构微通道中液滴变形运动的机理实验，系统研究流场中纳米颗粒吸附液滴的动力学行为，重点揭示界面粘弹性与纳米颗粒动态传输对液滴变形运动特性的影响机理，获得纳米颗粒吸附界面调控流场中液滴动力学行为的系统规律。研究成果将丰富多相流热物理学科液滴动力学的基础理论，同时为石油工程纳米驱油等技术的发展提供理论支撑。

针对表活剂、纳米颗粒等物质在油水界面吸附及其诱发的界面黏弹性等特殊力学性质可调控流场中液滴动力学行为的科学假设，本项目开展了系统研究。发展了复杂界面液滴动力学数值模拟方法，可同时考虑界面黏弹性等复杂界面力学性质、流体黏弹性等流体复杂流变性质、变截面通道等复杂孔隙结构等特殊性；研究了剪切流场、微通道流动等可控流场中的复杂液滴动力学行为，揭示了表活剂或纳米颗粒诱发的界面黏弹性、流体黏弹性等特性对液滴变形、破碎、运动等特性的影响规律及机理；搭建了微孔隙中液滴动力学研究的微流体可视化实验平台，研究获得了纳米颗粒表活剂对微通道中液滴生成、液滴融合等动力学的调控规律。项目研究结果可为石油工程中纳米驱油等提高采收率技术的发展提供理论支撑。以第一作者已发表国际期刊SCI论文4篇，包括J. Fluid Mech.期刊2篇、Phys. Fluids期刊1篇、Soft Matter期刊1篇；国际国内学术会议论文报告共15篇，其中国际会议特邀报告3次；培养在读博士生2名、在读硕士生2名；项目负责人骆政园于2018年12月晋升副教授，2018年获陕西省优秀博士学位论文奖，2019年获西安交通大学十大学术新人奖。