Frictional flow patterns shaped by viscous and capillary forces (FriicFlow)

流体和颗粒材料的流动和混合发生在广泛的过程中。在自然界中，海洋沉积物中的甲烷排放是温室气体的重要来源，其排放率与沉积物和以气泡或通道形式上升的甲烷气体之间的复杂相互作用密切相关。另一个例子是气体通过火山岩浆的迁移——一种固体晶体和液体熔体的混合物——气体输送的复杂流动模式的细节被认为会影响火山喷发的行为。在工程领域，颗粒悬浮物和可变形多孔材料的处理在石油和天然气、食品加工和制药等众多行业中都是关键。尽管这些过程丰富而重要，但在许多领域却缺乏控制它们的基本物理知识。由于颗粒材料、液体和气体在流动过程中发生了非常复杂的相互作用，这些系统本身就难以预测和控制。该项目的主要目的是揭示两种未知机制的物理学原理，即流体粘度和颗粒-流体相互作用在控制摩擦流体和可变形材料流动行为中的作用。通过实验和计算机模拟，我们将探索粘度比的全范围；将高粘度流体注入到低粘度宿主流体中，反之亦然，其中宿主流体含有一系列浓度、形状和大小的颗粒物质。在两种流体相遇的地方，半月板会根据颗粒的润湿特性(例如，颗粒是亲水（“亲水”）还是疏水（“憎水”）对颗粒进行推拉。通过与理论和模拟相匹配的精细控制实验，我们将揭示润湿对流动行为的影响。新的见解将被纳入模型中，从而可以更准确地预测摩擦流动行为，并最终改善对火山爆发等自然事件的预测，并优化颗粒悬浮液和可变形材料的工业处理。

Flow and mixing of fluids and granular materials occur in a wide range of processes. In nature, methane venting from ocean sediments represents a significant source of greenhouse gas, and the emission rate is intimately linked with complex interactions between the sediment and the rising methane gas in the form of bubbles or channels. Another example is the migration of gas through volcanic magma - a mixture of solid crystals and liquid melt - where the specifics of the complex flow patterning of the gas transport is thought to influence volcanic eruption behaviour. In the engineering sector, handling of granular suspensions and deformable porous materials are key in a wide range of industries from oil and gas, to food processing and pharmaceuticals. Despite the abundance and importance of such processes, fundamental knowledge of the physics that control them is lacking in many areas. These systems are inherently difficult to predict and control because of the very complex interactions taking place between the granular materials, liquids and gases during flow.The main aim of the project is to uncover the physics of two unknown mechanisms, namely the role of fluid viscosity and grain-fluid interactions in controlling the flow behaviour of frictional fluids and deformable materials. Using both experiments and computer simulations, we will explore the full range of viscosity ratio; high viscosity fluids injected into low viscosity host fluids and vice versa, where the host fluid contains granular materials of a range of concentrations, shapes and sizes. Where the two fluids meet, the meniscus will push or pull on the grains depending on the wetting properties, e.g. whether the grains are hydrophilic ("water-loving") or hydrophobic ("water-hating"). Through finely controlled experiments matched with theory and simulations we will reveal the effect of wetting on the flow behaviour. The new insight will be incorporated into models that will allow a much more accurate prediction of frictional flow behaviour, and ultimately to improving forecasting of natural events such as volcanic eruptions, and to optimize industrial processing of granular suspensions and deformable materials.