U.S.-Hungary Joint Fund Research: Convection Induced by Chemical Waves

这项美国-匈牙利联合基金关于“化学波引起的对流”的研究将由科苏斯科学大学的George Bazsa博士与南密西西比大学的John A.Pojman博士合作进行。自催化反应(其中产物提高自身的生产速度)可以在未搅拌的溶液中繁殖。这些反应可以通过释放热量(降低密度)和改变溶液的组成(增加或降低密度)来改变溶液的密度。在重力的影响下，产生的密度梯度可能会导致流体运动或自然对流。在铁-硝酸体系中，对流对锋面传播速度的影响表现出令人费解的对管取向和初始浓度的依赖关系。对流的机制目前还不清楚。除了提出有关化学和流体力学相互作用的基本问题外，这项工作还有助于理解其他领域中的化学诱导对流，如定向凝固和湿化学腐蚀。这项研究将使用视频成像技术测量旅行锋面上的浓度梯度和温度梯度，以检验所提出的对流机制，这些机制已经被观测到，而且通常只从传播测量中推断出来。化学诱导对流系统提供了对小容器中自然对流的洞察。流体流动相对于重力矢量的方向依赖性与空间中的材料加工特别相关，在太空中，重力降低，但控制容器相对于重力矢量的方向的难度更大。这项化学研究通过使美国和匈牙利的顶尖专家能够将互补的人才结合在一起，并在相互感兴趣和能力很强的领域汇集研究资源，实现了推动科学发展的计划目标。

This US-Hungary Joint Fund research on "Convection Induced by Chemical Waves" will be conducted by Dr. George Bazsa of Kossuth Science University in cooperation with Dr. John A. Pojman of the University of Southern Mississippi. Autocatalytic reactions (in which the products increase the rate of their own production) can propagate in unstirred solutions. The reactions can alter the density of the solution by releasing heat (decrease the density) and by changing the composition of the solution (either increase or decrease the density). Under the influence of gravity the resulting density gradients can result in fluid motion, or natural convection. The effect of convection on the rate of front propagation in the iron-nitric acid system has been shown to exhibit puzzling dependence on the orientation of the tube and the initial concentrations. The mechanism of the convection is still not clear. Besides raising basic questions about the interactions of chemistry and hydrodynamics, this work may aid in understanding chemically induced convection in other areas such as directional solidification and wet chemical etching. This study will measure the concentration gradients and thermal gradients in traveling fronts using video imaging technology in order to test mechanisms proposed for the convection which has been observed, and often, only inferred from measurements of propagation. Chemically induced convection systems offer insight into natural convection in small containers. The orientation dependence of fluid flow with respect to the gravitational vector is especially relevant to materials processing in space, where there is reduced gravity but greater difficulty in controlling the orientation of the container with respect to the gravitational vector. This research in chemistry fulfills the program objective of advancing science by enabling leading experts in the United States and Hungary to combine complementary talents and pool research resources in areas of strong mutual interest and competence.