Utilising a Naturally Occurring Drag Reduction Method

现在很明显，全球气候正在发生变化。2018年10月，联合国洲际气候变化专门委员会发布了一份关于全球变暖影响的特别报告。该报告指出，为了到2050年实现二氧化碳的“净零”排放，需要进行“迅速而深远”的变革。目前，二氧化碳排放的最大来源之一直接来自为运输目的燃烧化石燃料。仅海运每年就排放约9.4亿吨二氧化碳，占全球温室气体排放总量的2.5%左右。众所周知，造成全球燃料消耗（以及温室气体排放）的一个主要因素是表面摩擦阻力。该力与所有物体在流体中移动时所经历的阻力相关联。无论流体是空气、水还是其他流体，表面摩擦阻力总是存在的，并且需要能量来克服其影响。这包括人类在竞技游泳和自行车运动中的能量输入。鉴于全球变暖的有形有害影响和相关的社会后果，近几十年来，对用于减少汽车、飞机、船舶中的皮肤摩擦阻力的技术的研究已经加强。这些减阻技术的灵感来源之一来自对飞行员和游泳者的研究。为了生存，鸟类和鱼类已经适应了数千年。科学家们最感兴趣的正是这些适应性。更具体地说，研究界关注的是进化确保了这些物种在以流体为中心的栖息地中有效地移动。一个相对较新的例子，已经获得了大量的关注，从流体力学是减少皮肤摩擦阻力，通过引入鲨鱼皮肤一样的粗糙表面时，连接到柔性膜，特别是。边界层流动是在边界表面之上或之下的流体薄层的流动。这些类型的流动是普遍存在的，并且可以直接受到表面摩擦阻力的影响。该项目将从理论上研究边界层流动可以通过在自然界中观察到的生物启发的减阻技术来主动控制的想法。调查的目标将是开发数学技术，可用于模拟控制这种流动的能力，特别是延迟湍流过渡的开始。湍流在降低燃料效率方面起着重要作用，并且在燃烧化石燃料的发动机的情况下，在增加有害的CO2排放方面具有相关的影响。关于道路上越来越多的电动车辆以及相关的英国政府停止柴油和汽油车辆生产的进展，改进的减阻技术将产生改进的范围性能，目前公众认为这是不容易采用该技术的原因。这项研究的结果将为主动流量控制方法提供新的见解，这些方法可以用来减少阻力的影响，并改善全球燃料消耗，从而带来经济效益。

It is now evident that the global climate is changing. In October of 2018, the United Nations (UN) Intercontinental Panel on Climate Change issued a special report on the impacts of global warming. The report notes that "rapid and far-reaching" changes will be required in order to achieve "net-zero" CO2 emissions by 2050. At present, one of the largest sources of CO2 emissions stems directly from the burning of fossil fuels for transportation purposes. Maritime transport alone emits around 940 million tonnes of CO2 annually and is responsible for around 2.5% of the total global greenhouse gas emissions. It is well understood that a major contributing factor to this worldwide fuel consumption (and, by proxy, greenhouse gas emissions) is skin-friction drag. This force is associated with the drag that all bodies experience as they move through a fluid. Whether that fluid be air, water or otherwise, skin-friction drag will always be present and energy is required to overcome its effect. This includes human energy input in competitive swimming and cycling.Given the tangible detrimental effects and related societal consequences of global warming, research into techniques that act to reduce skin-friction drag in cars, aeroplanes, ships has intensified in recent decades. One source of inspiration for these drag reduction techniques has come from the study of fliers and swimmers. For the purposes of survival, birds and fish have been adapting for many millennia. It is these adaptations that have most interested scientists. More specifically, the research community has focused on the idea that evolution has ensured that these species move incredibility efficiently through their fluid-centred habitats. A relatively recent example that has garnered a great deal of attention from fluid mechanists is the reduction of skin-friction drag via the introduction of shark-skin-like rough surfaces when attached to flexible membranes, in particular. A boundary-layer flow is the flow of a thin layer of fluid above or below a bounding surface. These types of flow are pervasive and can be directly affected by skin-friction drag. This project will investigate, theoretically, the idea that boundary-layer flows can be actively controlled via biologically-inspired drag reduction techniques observed operating in the natural world. The goal of the investigation will be to develop mathematical techniques that can be used to model the control of such flows with a specific focus on the ability to delay the onset of turbulent transition. Turbulent flows play a significant role in reducing fuel efficiency and, in the case of fossil-fuel burning engines, have an associated impact in increasing harmful CO2 emissions. In relation to the increasing number of electrical vehicles the road and the associated UK Government's advancement of the cessation of diesel and petrol vehicle production, improved drag reduction techniques would produce improved range performance, that at present to the public is a perceived reason for not readily adopting the technology. The results that stem from this study will provide new insights into active flow control methods which can then be utilised to reduce the effects of drag and improve global fuel consumption with resultant economic benefits.