Chemistry in Flow: Amplification versus Extinction

化学反应与输送过程的耦合在生物学、工程学和大气科学等许多学科中都有重要意义。许多反应显示出自催化作用，其中反应的产物，即活化剂，催化其自身的生成。自催化作用为化学信号的放大和传播提供了重要的机制。化学和流动联合收割机在微观到宏观的长度尺度上产生了生物模式的形成，从变形虫泡囊中细胞内容物的运动（流动）到海洋流动中浮游生物群落的生长（开花）。特别重要的是反应在开放流中持续的条件。自催化反应通常以全有或全无的方式响应;反应被放大，可能导致空间分布的反应热点，或被流动熄灭。已经证明，即使湍流也包含一定程度的相干性，例如涡流，这可能为物种的局部混合和反应放大创造条件。然而，虽然理论正在迅速出现，但几乎没有实验数据来区分它们。该项目的目的是通过紧密结合的实验和理论研究方案来解决这一真空。这里提出的跨学科研究将研究自催化化学和流动的相互作用，重点关注微观结构流动对宏观化学活性的影响。我们的目标是产生受控的实验室研究，以量化相干流对反应放大的作用。我们的研究将为复杂流动系统中的化学反应动力学提供一个新的视角。在这个项目中，我们将：（a）使用磁共振成像（MRI）来可视化管流，涡流和混沌流场中的自催化化学反应，并量化反应被放大的条件（B）发展理论和模型耦合自催化化学反应与相干流场（c）表征相干流环境中空间秩序的出现这个项目将产生：（1）用于流动中化学反应的MRI研究的实验协议MRI是唯一能够同时可视化化学反应和探测反应介质的传输特性。MRI还能够探测使用光学方法无法达到的流动几何形状中的化学放大。这项技术将为我们提供化学波的3D图像，并允许我们将实验实现的流动转移到反应的数值模拟中。MRI还提供了使用磁场最终操纵局部化学结构的可能性。(2)将自催化化学反应与2D和3D流场耦合的计算模型模型使我们能够生成可能难以通过实验获得的数据，预测复杂系统的行为并指导实验研究。白色玫瑰网格（http：//www.wrgrid.org.uk/）是一个高性能计算设施，跨越利兹，约克和谢菲尔德大学，是一个卓越的电子科学中心。利兹的研究人员非常适合利用这种计算设施，使用在伯明翰产生的实验数据来验证，开发和改进模型。

The coupling of chemical reaction with transport processes is important in a wide variety of disciplines such as biology, engineering and atmospheric science. Many reactions display autocatalysis, in which a product of the reaction, the activator, catalyses its own production. Autocatalysis provides an important mechanism for the amplification and propagation of a chemical signal. Chemistry and flow combine to give rise to biological pattern formation on microscopic to macroscopic length scales, from the movement of cellular contents (streaming) in the amoeboid physarum to the growth of plankton colonies (blooming) in oceanic flows. Of particular importance are the conditions for which a reaction is sustained in open flow. Autocatalytic reactions generally respond in an all-or-nothing fashion; the reaction is amplified, possibly resulting in spatially-distributed reaction hot spots , or extinguished by the flow. It has been demonstrated that even turbulent flows contain some degree of coherence, such as vortices, that may create conditions for localised mixing of species and reaction amplification. However, while theories are emerging rapidly there is little experimental data to distinguish between them. The aim of this project is to address this vacuum via a closely coupled experimental and theoretical programme of research.The interdisciplinary research proposed here will examine the mutual interaction of autocatalytic chemistry and flow, focussing on the influence of micro-structured flow on macroscopic chemical activity. Our goal is to produce controlled laboratory studies to quantify the role of coherent flow on reaction amplification. Our research will provide an insight to the dynamics of chemical reaction in complex flow systems. In this project we will:(a) Use Magnetic Resonance Imaging (MRI) to visualise autocatalytic chemical reaction in pipe-flow, vortices and chaotic flow fields and quantify the conditions for which the reaction is amplified(b) Develop theory and models coupling autocatalytic chemical reaction with coherent flow fields(c) Characterise the emergence of spatial order in coherent flow environmentsThis project will produce:(1) Experimental protocols for MRI investigation of chemical reaction in flowMRI is uniquely able to simultaneously visualise chemical reaction and probe transport properties of the reaction media. MRI is also able to probe chemical amplification in flow geometries inaccessible using optical methods. This technique will provide us with 3D images of chemical waves, and allow us to transfer experimentally-realised flows into numerical simulations of the reaction. MRI also presents the possibility for the eventual manipulation of the localised chemical structures using magnetic fields. (2) Computational models coupling autocatalytic chemical reaction with 2D and 3D flow fieldsModels allow us to generate data that might be difficult to obtain experimentally, predict how complex systems will behave and steer experimental investigations. The White Rose Grid (http://www.wrgrid.org.uk/) is a high performance computing facility that spans Leeds, York and Sheffield Universities and is an e-Science Centre of Excellence. The Leeds investigators are ideally placed to utilise this computational facility, using experimental data generated in Birmingham to validate, develop and improve the models.