Fluid Flow and Heat and Mass Transfer in Micro-systems with Complex Physics

微设备中的流体流动和传热传质在环境、工业、生物和生物医学系统的利用、检测、传感、监测和诊断中具有许多工程应用。人们需要廉价、可靠、实时的设备来诊断疾病、监测对环境有害的气体、探测生物和化学战剂等。当前提案的重点将是研究微流体系统中流动和液滴的物理特性。需要开发数学模型和仿真工具。新创造的知识有助于更好地理解液滴微设备的操作，改进新型诊断设备的设计，如流动聚焦和数字液滴设备，并开发新技术。从长远来看，它旨在扩大我们在开发工业和环境监测设备方面的成果。微流控和纳米流控装置已成为疾病诊断的有力工具。不同类型的微流控装置在不同几何结构下的广泛应用已经得到了广泛的研究。然而，大多数工作都是通过反复试验来优化这些设备的操作。流动为层流，混合过程主要受缓慢扩散机制控制。流体流动也与液滴呈两相或多相流动。混合过程通常由施加的外力进行，如电、热、磁或声。两相或多相流和/或多组分流的主题在计算上是一项非常具有挑战性的任务。大多数分析都是基于经验相关性和非精确科学。此外，在微观和纳米尺度上的流固相互作用尚未完全了解。这个问题在额外的物理条件下变得更具挑战性，比如电磁力、焦耳加热、非定常流等。因此，有必要了解和发展问题的坚实基础物理，并为这些设备的模拟开发一个数学模型。***仿真结果帮助我们理解物理和控制参数的影响。此外，仿真在这类器件的优化过程中具有成本效益。传统的CFD方法在处理多相流时存在许多局限性。另一方面，晶格玻尔兹曼方法（LBM）是解决流体动力学问题的一种非常强大的替代方法。在LBM中，将热力学与输运方程相结合是比较容易的。此外，它编码简单，可以很容易地与并行处理器计算机一起使用。研究结果将有助于开发新颖、可靠、实时、基于液滴的微流体装置，用于许多应用。其结果将有利于加拿大经济。

Fluid flow and heat and mass transfers in micro devices have many engineering applications in utilizing, detecting, sensing, monitoring, and diagnosis of environmental, industrial, biological, and biomedical systems. There is a need for cheap, reliable, real-time devices to diagnose diseases, monitor environmentally harmful gases, detect biological and chemical warfare agents, etc. The focus of the current proposal will be on investigating the physics of flow and droplets in microfluidic systems. Mathematical models and simulation tools need to be developed. The newly created knowledge leads to better understanding the operation of droplet micro devices, improve the design of novel diagnostic devices, such as flow focusing and digital droplet devices, and in developing a new technology. In the long term, it is intended to expand our results for developing industrial and environmental monitoring devices. ***Microfluidic and Nanofluidic devices have emerged as potent instruments for diagnosis of diseases. Extensive research has been done on different types of microfluidic devices for a wide spectrum of applications with different geometrical configurations. However, most of the works are done by a trial and error to optimize the operation in those devices. The flow is laminar, where the mixing process is mainly controlled by a slow diffusion mechanism. The fluid flow is also in two or multi-phases with droplets. The mixing processes are usually carried out by an applied external force, such as electric, thermal, magnetic, or acoustic. The topic of two or multi-phase and/or multicomponent flows is a very challenging task, computationally. Most analysis has been based on empirical correlations and non-exact science. Moreover, the fluid-structure interaction on micro- and nano-scales is not fully understood. The problem becomes more challenging with extra physics, such as electrical force, Joule heating, unsteady flows, etc. Hence, there is a need to understand and develop solid underlying physics of the problem and develop a mathematical model for simulations of those devices.***The simulation results help us to understand the physics and the effects of the controlling parameters. Also, simulation is cost effective in the optimization process of such devices. Conventional CFD methods have many limitations when it comes to dealing with multi-phase flows. On the other hand, the Lattice Boltzmann method (LBM) is a very powerful alternative method compared with the conventional methods to solve fluid dynamics problems. In LBM, it is relatively easy to integrate thermodynamics with transport equations. Besides, it enjoys simple coding and can be easily used with parallel processor computers. The outcome of the research will help in developing novel, reliable and real-time, droplet-based microfluidic devices for many applications. The outcomes will contribute to the Canadian economy.