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

这项关于“化学波诱导对流”的美匈联合基金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（产物提高自身生产速率）可以在未搅拌的溶液中进行。这些反应可以通过释放热量（降低密度）和改变溶液的组成（增加或减少密度）来改变溶液的密度。在重力的影响下，产生的密度梯度会导致流体运动或自然对流。在铁-硝酸体系中，对流对锋面传播速率的影响已被证明对管的方向和初始浓度具有令人费解的依赖性。对流的机理尚不清楚。除了提出关于化学和流体动力学相互作用的基本问题外，这项工作可能有助于理解定向凝固和湿化学蚀刻等其他领域的化学诱导对流。本研究将使用视频成像技术测量行进锋面的浓度梯度和热梯度，以测试对流的机制，这些机制已经被观察到，并且通常只能从传播的测量中推断出来。化学诱导对流系统提供洞察自然对流在小容器。流体流动相对于重力矢量的方向依赖关系与空间中的材料加工特别相关，在空间中，重力减小，但在控制容器相对于重力矢量的方向方面难度更大。这项化学研究实现了促进科学发展的计划目标，使美国和匈牙利的领先专家能够在共同感兴趣和能力强的领域结合互补的人才和集中研究资源。

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.