Temporal and Spatiotemporal Dynamics of Chemical Reactors

振荡在化学系统中被发现已经有一段时间了，在这种系统中会出现状态分岔、混沌和复杂的空间模式等现象。在混合良好的开放反应系统中（例如连续搅拌槽式反应器），反应物质的浓度可以经历周期性和混沌振荡。催化表面反应，如一氧化碳的氧化（发生在汽车的催化消声器中的反应之一），也可以在催化表面上振荡并产生空间图案。电化学反应，如金属的电溶解或腐蚀，可以表现出反应速率的时间和空间变化。PI的工作重点是量化上述实验观察到的行为和发展定量现象学模型。将要研究的反应在工业和经济上都很重要，并将有助于提高对这些反应过程的基本理解。电化学反应有几个特点，使其成为反应动力学基础研究的理想选择。它们是相对平稳的，即在动力学的时间尺度上有较小的漂移，它们表现出许多有趣的动态行为，如复杂的周期振荡、低阶混沌、时空模式等。此外，还有易于控制的参数（电势或电流以及旋转圆盘附近的传质系数），因此可以研究状态之间的转换。PI将研究化学反应系统的时间和时空动力学。在时间研究中，将研究金属电化学溶解产生的时间序列。这些研究既要具有确定性，也要具有随机性。在前者中，将强调状态之间的混沌行为和过渡或分岔，将非线性动力学方法应用于实验数据，以识别和表征系统的潜在动力学并开发现象学数学模型。将启动一个新的电化学噪声与局部腐蚀相关的研究项目，包括实验和模型研究。时空动力学将通过使用摄像机记录空间不均匀性来研究。这项工作的目的是建立模型，以帮助回答诸如薄膜是如何在溶解金属上生长和消退的问题，腐蚀金属表面的凹坑之间有多少相互作用，以及在什么条件下局部或全局的反应地点是同步的。＊＊＊

Abstract - Hudson - 9416938 Oscillations have been known in chemical systems for some time, phenomena such as bifurcations among states, chaos, and complex spatial patterns can arise in such systems. In well-mixed open reacting systems (for example a continuous stirred tank reactor) the concentrations of reacting species can undergo periodic and chaotic oscillations. Catalytic surface reactions such as the oxidation of carbon monoxide (one of the reactions taking place in the catalytic muffler of an automobile), can also oscillate and produce spatial patterns on the catalytic surface. Electrochemical reactions, such as electrodissolution of metals, or corrosion, can exhibit temporal as well as spatial variations in reaction rate. The PI's work is focused on quantifying the above experimentally observed behavior and on developing quantitative phenomenological models. The reactions that will be studied are of both industrial and economic importance and should lead to an improved fundamental understanding of such reaction processes. Electrochemical reactions have several features which make them ideal for fundamental studies of reaction dynamics. They are relatively stationary, i.e., have less drift over the time scale of the dynamics and they exhibit many types of interesting dynamic behavior such as complex periodic oscillations, low order chaos, spatiotemporal patterns, etc. Also, there are easily controlled parameters (the potential or current as well as the mass transfer coefficient near a rotating disk) so that transitions among states can be investigated. The PI will study the temporal and spatiotemporal dynamics of chemically reacting systems. In the temporal studies, time series emanating from the electrochemical dissolution of metals will be investigated. The studies are to be both deterministic and stochastic. In the former, chaotic behavior and transitions, or bifurcations, between states will be emphasized, applying methods from nonlinear dynamics to the experimental data in order to identify and characterize the underlying dynamics of the system and to develop phenomenological mathematical models. A new research program in electrochemical noise associated with localized corrosion will be initiated, consisting of both experimental and modeling studies. Spatiotemporal dynamics will be studied by using a video camera to record spatial nonuniformities. The work is aimed at developing models which should help answer questions such as how do films grow and recede on dissolving metals, how much interaction is there among pits on the surface of corroding metals, and under what conditions is synchronization among reacting sites local or global in nature. ***