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.
