自催化羽流夹断
Autocatalytic plume pinch-off
摘要：
非反应性流体介质中的浮力通量的局部源产生羽流。通量可以通过热、包括羽流的流体与其周围环境之间的成分差异或两者的组合来提供。然而，对于由碘酸-亚砷酸反应产生的自催化羽流，浮力沿着羽流与其周围环境之间的整个反应界面产生。在移动界面处产生的浮力驱动流体运动，流体运动进而产生对流反应前沿的流动。由于流体流动和化学反应之间的这种相互作用，自催化羽流在通过反应物介质的上升过程中表现出丰富的动力学。一个更有趣的动力学特征是产生一个加速的旋涡羽流头，在某些情况下，夹断和分离的上升流管道。夹断之后，在下方的管道中形成新的羽流头部，并且这可以导致对于单个羽流引发的多代羽流头部。我们研究了夹断过程中使用实验和模拟。使用各种浓度的甘油进行实验，其中发现重复夹断仅在特定浓度范围内发生。自催化羽流模拟表明，夹断是由羽流导管中的加速流的出现触发的。
英文摘要：
A localized source of buoyancy flux in a non-reactive fluid medium creates a plume. The flux can be provided by either heat, a compositional difference between the fluid comprising the plume and its surroundings, or a combination of both. For autocatalytic plumes produced by the iodate-arsenous acid reaction, however, buoyancy is produced along the entire reacting interface between the plume and its surroundings. Buoyancy production at the moving interface drives fluid motion, which in turn generates flow that advects the reaction front. As a consequence of this interplay between fluid flow and chemical reaction, autocatalytic plumes exhibit a rich dynamics during their ascent through the reactant medium. One of the more interesting dynamical features is the production of an accelerating vortical plume head that in certain cases pinches-off and detaches from the upwelling conduit. After pinch-off, a new plume head forms in the conduit below, and this can lead to multiple generations of plume heads for a single plume initiation. We investigated the pinch-off process using both experimentation and simulation. Experiments were performed using various concentrations of glycerol, in which it was found that repeated pinch-off occurs exclusively in a specific concentration range. Autocatalytic plume simulations revealed that pinch-off is triggered by the appearance of accelerating flow in the plume conduit.
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