Controlling viscous fingering with fluid-structure interactions

粘性指指是一种典型的流体动力学不稳定性，当流体被注入多孔介质或已经含有更粘性流体的Hele-Shaw细胞时，就会发生这种不稳定性。其结果是，入侵流体将以狭窄的手指状通道穿过防御流体，而不是均匀地取代防御流体。与大多数不稳定性一样，粘性指进可能是可取的，也可能是不可取的——例如，它对提高石油采收率和许多制造过程有强烈的不利影响，但它也可以用来促进微流体装置中的混合。在这些和其他应用中，能够抑制、增强或以其他方式控制这种现象将是非常有用的。控制流体动力不稳定性（如粘性指动）的前景是整个工程领域长期面临的挑战。实现这一目标的一种有希望的方法是通过使用可移动或可变形的固体结构来操纵流。以前通过这种流固相互作用（FSI）控制不稳定性的大多数努力都是针对惯性流动（例如，气动阻力和湍流），但这个想法也与粘性流动（例如，微流体，生物医学工程和地下流动），包括粘性指指有明显的相关性。该项目的目标是加强和扩大我们对FSI对粘性流动的影响的理解，特别是对粘性指法的影响。我们将首先开发一种新型装置，用于测量和控制Hele-Shaw池中FSI对粘性流动的影响。然后，通过将该系统中的高分辨率实验与数学建模相结合，我们将开发一种新的控制粘性指指的策略。这种增强或抑制粘性指指的策略可以应用于各种实际挑战，从微流体到提高石油采收率。

Viscous fingering is a classical hydrodynamic instability that occurs when a fluid is injected into a porous medium or Hele-Shaw cell that already contains a more viscous fluid. The result is that the invading fluid will propagate through the defending fluid in narrow, finger-like channels rather than displacing it uniformly. As with most instabilities, viscous fingering can be desirable or undesirable---For example, it has a strong and adverse impact on enhanced oil recovery and many manufacturing processes, but it can also be exploited to promote mixing in microfluidic devices. In these and other applications, it would be extremely useful to be able to suppress, enhance, or otherwise control this phenomenon.The prospect of controlling hydrodynamic instabilities such as viscous fingering is a long-standing challenge across engineering. One promising approach for achieving this is by manipulating the flow with a moveable or deformable solid structure. Most previous efforts to control instabilities via such fluid-structure interactions (FSI) have been directed at inertial flows (e.g., aerodynamic drag and turbulence), but this idea also has clear relevance to viscous flows (e.g., in microfluidics, biomedical engineering, and subsurface flow), including viscous fingering.The goal of this project is to strengthen and broaden our understanding of the impact of FSI on viscous flows in general, and on viscous fingering in particular. We will first develop a novel apparatus for measuring and controlling the impact of FSI on viscous flow in a Hele-Shaw cell. Then, by combining high-resolution experiments in this system with mathematical modelling, we will develop a new strategy for controlling viscous fingering. This strategy for enhancing or suppressing viscous fingering can then be applied to a wide variety of practical challenges, from microfluidics to enhanced oil recovery.