权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

The Propagation of Wetting Fronts Through Porous Media

润湿锋通过多孔介质的传播

基本信息

批准号：
EP/G048916/2
负责人：
James Sprittles
金额：
$ 5.37万
依托单位：
University of Oxford
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2012
资助国家：
英国
起止时间：
2012 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FG048916%2F2
关键词：
Propagation Wetting Fronts Through Porous

项目摘要

This research is concerned with the flow of liquid through solids which are permeated by a network of holes; such materials are known as porous media. Understanding how a liquid will flow through a porous structure is also the key element to a range of industrial phenomena such as:- The recovery of oil from a reservoir. This is currently a highly inefficient process with at most half of the possible oil recovered from each well.- The storage of carbon dioxide deep underground in a porous medium in an attempt to reduce global warming. Here it is vital to ensure that harmful gases will not escape over a period of hundreds of years.- The seeping of a liquid ink-jet droplet into paper where, to ensure quality of the image, it is desirable to know how quickly the paper will absorb the ink.Often a full scale experiment of such a flow is unpractical, expensive and/or dangerous. Consequently theoretical modelling becomes a tool which can be used to probe the dynamics of such flows to ensure safety, insight and optimisation of the appropriate process. There has been intensive academic research in this field from the mid-nineteenth century when Henry Darcy, motivated by the need to provide clean water for the citizens of Dijon, proposed an equation to describe the flow of water through sand. Amazingly this equation is still used for most porous media flows.Our research concerns the motion of a liquid into an initially dry porous medium. This often occurs spontaneously, for example, you can observe a liquid creeping slowly up a biscuit which is placed in a cup of tea. The reason that the liquid climbs up through the porous medium, against the downward pull of gravity, is that the liquid's surface has a stronger affinity for the solid than it does for the rest of the liquid, creating what is known as a capillary force, dragging the liquid further into the solid.Capillary effects occur in a wide range of phenomena, they are responsible for the spherical shape of bubbles, the ability of small animals to walk on water and the tears of wine on a glass. Perhaps the easiest way to observe their power is to place a small cylindrical tube vertically into a bath of water and observe that the water inside the tube is above that of the bath. In fact the simplest model for flow into an initially dry porous medium is obtained by approximating the medium as a bundle of capillary tubes. It is assumed, rather crudely, that the capillary force propelling the front of the liquid into the porous medium is equal to its equilibrium value. This approach was originally proposed by Washburn in 1921. Although describing the incredibly complex structure of a porous medium in this simplified approach leads to surprisingly accurate results, there is a large body of experimental evidence suggesting that it is often inaccurate.The project proposes a transfer of knowledge from the neighbouring field of dynamic wetting, which is concerned with the flow of liquids on solids, to the class of problems we are interested in, namely the flow of liquids into solids. Recent experimental results in the dynamic wetting community have shown how many industrial processes can be optimised in a way which was not previously realised. This was originally discovered in the photographic industry where it was demonstrated how to coat a solid with a liquid layer as fast as possible without ruining the film's quality by entraining air bubbles into it.The theory which predicts this phenomenon has only been thoroughly explored in the field of dynamic wetting in the past few years and has never been applied to flows through porous media. By applying the advanced mathematical model behind this theory to the propagation of a liquid through a network of pores we hope to improve on the current model for describing flow into a dry porous medium and bridge the gap between the two communities.

这项研究是关于液体在由孔洞网络渗透的固体中的流动；这种材料被称为多孔介质。了解液体如何流过多孔结构也是一系列工业现象的关键因素，例如：-从油藏中开采石油。目前，这是一种效率极低的方法，每口井最多只能回收一半的原油。-将二氧化碳储存在地下深处的多孔介质中，以减缓全球变暖。在这里，确保有害气体在数百年的时间内不会逸出是至关重要的。-液体喷墨滴渗入纸张的过程，为了保证图像质量，我们需要知道纸张吸收墨水的速度。通常，对这种流体进行全面的实验是不切实际的、昂贵的和/或危险的。因此，理论建模成为一种工具，可以用来探测这种流动的动态，以确保安全，洞察力和适当过程的优化。从19世纪中期开始，这一领域就有了深入的学术研究，当时亨利·达西（Henry Darcy）出于为第戎市民提供清洁水的需要，提出了一个方程来描述水在沙子中的流动。令人惊讶的是，这个方程仍然用于大多数多孔介质的流动。我们的研究涉及液体进入最初干燥的多孔介质的运动。这通常是自发发生的，例如，你可以观察到一种液体慢慢地爬上放在一杯茶中的饼干。液体之所以会在向下的重力作用下，在多孔介质中向上攀爬，是因为液体的表面对固体的亲和力比液体的其他部分更强，从而产生了所谓的毛细力，将液体进一步拉入固体。毛细效应存在于各种各样的现象中，它们导致了气泡的球形、小动物在水面上行走的能力和酒杯上酒的眼泪。也许观察它们的力量最简单的方法是将一个小的圆柱形管垂直地放入一盆水中，观察管内的水高于浴缸的水。事实上，流体进入最初干燥的多孔介质的最简单模型是将介质近似为一束毛细管。我们相当粗略地假定，推动液体前部进入多孔介质的毛细力等于它的平衡值。这种方法最初是由Washburn在1921年提出的。尽管用这种简化的方法描述多孔介质的复杂结构会得到令人惊讶的精确结果，但大量的实验证据表明，这种方法往往是不准确的。该项目提出了一种知识转移，从邻近的动态润湿领域，这是有关液体在固体上的流动，到我们感兴趣的一类问题，即液体进入固体的流动。最近在动态润湿社区的实验结果表明，有多少工业过程可以以一种以前没有实现的方式进行优化。这最初是在摄影工业中发现的，当时人们演示了如何在不损坏胶片质量的情况下，尽可能快地在固体表面涂上一层液体层。预测这一现象的理论在过去几年里只是在动态润湿领域进行了深入的探索，从未应用于多孔介质的流动。通过将这一理论背后的先进数学模型应用于液体通过孔隙网络的传播，我们希望改进当前描述流入干燥多孔介质的模型，并弥合两个群体之间的差距。