Title: Phase Defect Description of Traveling-Wave Convection
Speaker: Professor C. Surko
Speaker Info: U. California, San Diego
Special Note: Note: unusual day!
Convection is studied in a horizontal layer of a binary fluid mixture of ethanol and water. In such mixtures, the coupling between the temperature and concentration fields leads to dynamical behavior not observed in pure fluids. Two different regimes will be discussed. The talk will focus on the regime in which the effects of concentration are stabilizing, and convection takes the form of traveling waves. The system then provides an insightful model for studying traveling-wave phenomena in systems driven far from equilibrium. Studies will be described of the relaxation of turbulent traveling-wave states, which is a kind of phase turbulence. We have found that the evolution of the patterns can be described in terms of topological defects in the phase field. Possible ingredients a predictive model of traveling-wave dynamics in terms of these phase defects will be discussed. When the mixture is heated from above, a very different flow is generated which has similarities to thermohaline convection in salty water. Results in this regime will be briefly summarized.Date: Wednesday, May 12, 1999