Active Control of Flow Patterns: Often, in industrial processes and in propulsion, fluids behave in an undesirable way. For example, oscillatory convection in a crystal melt leads to defects in the crystal. Conversely, in chemical reactions and combustion, it is desirable to maintain chaotic and turbulent flows to achieve vigorous mixing. Applying ideas of control theory, we are studying experimentally and theoretically the feasibility of modifying flow patterns so as to achieve optimal flow conditions for various processes. For example, with the use of a feedback controller effecting small perturbations in boundary conditions, we have been able to maintain laminar flows under conditions in which chaotic flows would normally occur and conversely, induce chaos under conditions when the flow would normally tend to be laminar. Micro-fluidics: In experiment and theory, we are studying transport processes in very small devices and we are developing various microfluidic components. The objective is to develop the necessary science base needed to accommodate biological and chemical laboratories on a \"chip.\" Among other things, we are developing micro mixers, inertial separators of particles, thermal cyclers, and electrophoretic cells. Most recently, our efforts have focused on constructing MEMS devices on low-temperature, co-fired, ceramic tapes.
