Investigations of particle dynamics and their interaction with the carrying flow in micro systems

多相流是一种复杂的系统，其中一种液体拖拽着气态、液态或固态的其他组分。它们在自然界和工业过程中无处不在，是流体物理学中最具科学挑战性的问题之一。另一方面，新的小型化技术允许减少许多感兴趣的流体系统的尺寸，但他们需要更深入地了解多相流在这些尺度上的行为。该领域最大的问题之一是流动的稳定性以及向混沌和湍流的过渡。微流体流动不会进入湍流区，但一些作者认为，无论系统的规模如何，微多相流都可能进入混沌区。然而，这一课题尚未在受限系统中得到详细的研究。我们的第一个结果揭示了有趣的模式，需要更详细地研究。与小规模系统直接相关的是堵塞问题，特别是在处理微流体装置中的悬浮液时。令人惊讶的是，这个话题在微流体的文献中只得到了很少的讨论。我们的目的是找到与干燥颗粒系统中众所周知的筒仓堵塞或拱起问题的相似之处，并应用类似的技术来疏通或防止堵塞。

Multiphase flows are complex systems in which a liquid drags other components in gaseous, liquid or solid state. They are ubiquitous in nature and industrial processes and they are one of the most scientific challenges in fluid physics. On the other hand, the new miniaturization techniques permit to reduce the size of many fluidic systems of interest, but they require a deeper understanding on how multi-phasic flows behave at these scales. One of the biggest questions in this field is the stability of the flow and the transition to chaos and turbulence. Microfluidic flows do not enter in turbulent regimes, but some authors have suggested that micro-multi-phasic flows might enter into chaotic flow regimes regardless the scale of the system. However, the topic has not been studied in detail in confined systems. Our first results reveal interesting patterns that need to be studied in more detail. Directly related with small scale systems is the problem of clogging, specially when dealing with suspensions in microfluidic devices. Surprisingly, the topic has only been treated marginally in the literature on microfluidics. Our aim is to find the analogies with the well-known problem of silo clogging or arching in dry granular system, and apply similar techniques to unclog or to prevent the clogging.