This proposal focuses on multiphase flows. The first part of the project is a study of fluid-fluid interfaces which, on small scales, are dominated by surface tension. Such flows are relevant to the dynamics of emulsions, bubbles, drops and micro-fluidic devices. Highly accurate numerical simulations will be employed to describe the dynamics of drops merging or forced through micro-pipes. A novel approach to direct simulations of spatially varying surface tension will be presented. The simulations will be used to explore the potential of Marangoni flows to generate mixing in micro-drops. The second part of the project is concerned with interactions between small solid particles and their surrounding fluid, which are determinant in a variety of natural systems such as rivers, oceans, and the atmosphere. Numerical simulations will explore the mechanism by which particulate matter is eroded by an overlying fluid. The capacity of settling particles to transport heat in an advective rather than diffusive manner, without generating large scale fluid motion, will also be examined. The overall goal is to develop tools to investigate these complex physical systems and extract a fundamental understanding of basic phenomena at play in multiphase flows.
The research described in this proposal will be conducted at Merced, the newest campus (opened in 2005) of the University of California. It is the only research university of the Central Valley, and the student body is both diverse and traditionally under-represented at the university level. This project will provide research opportunities to both undergraduate and graduate students. The first topic studied involves the interaction of liquids and gases with other liquids, as is the case in drops and bubbles. Special emphasis will be placed on obtaining an understanding of the behavior of drops in the presence of temperature variations in ?lab-on-a- chip? systems, which allow controlled reactions to be studied on the micron scale. A second field of study will be the interaction of fluids with small solid particles, such as sand and sediments. The mechanism by which fluid flow can erode deposited particles, and the capacity of settling particles to affect heat transport will be investigated in detail. Broadly applicable new techniques will be developed to simulated these systems accurately and efficiently.
