中文摘要：

针对复杂的多相流动体系,构建了一套用于计算多相微流体的格子波尔兹曼模型方程,成功地对方形通道中的液滴流动进行了三维模拟,并对直通道和弯曲通道中不同的流动、混合机制进行了讨论。结果表明：在直通道中,混沌对流仅轴对称地发生在液滴中心轴的两侧,2个半区之间的混合仍通过分子扩散进行。在弯曲通道中,由于通道的几何转向,液滴流经通道时内部的流体会得以重新分布,内环流使得液滴内流体更为有效地进行混合。这种弯曲通道中的液滴内部的环流现象,可以强化微流体系统中的混合行为与反应行为。通过模拟的方法,揭示了微通道中液滴内部的流动机制,为微流动装置的设计和优化提供了理论基础。

英文摘要：

Numerical simulation of the multiphase flows in square-shaped micro-channels based on Lattice Boltzmann method （LBM） has been carried out. Special attention was paid to velocity fields inside the droplets moving in a straight and a winding micro-channel. The three-dimensional hydrodynamics of the liquid-liquid flow were obtained with detailed information inside micro-droplets. In the straight channel,the mixing inside the droplet occurred by convection through two symmetric vortices and mainly by diffusion between the two semi-spheres of the droplet. Whereas in the winding channel,the fluid inside the droplet was re-oriented due to the winding direction of droplet movement,which resulted in more effective mixing by recirculations. This work successfully revealed the flow mechanism inside the droplets in droplet-based microfluidics and is very helpful for the micro-device design and optimization.