International Research Fellowship Program: Effects of Lift Forces and Turbulence on Bubble Motion

Shew Woodrow L, College Park MD

Investigators

Abstract

0401986 Shew The International Research Fellowship Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a seventeen-month research fellowship by Dr. Woodrow L. Shew to work with Dr. Jean-Francois Pinton at Ecole Normale Superieure de Lyon in France. Gas-liquid flows play a crucial role in a diverse range of medical, industrial, and natural settings. In the medical setting, bubbles are known to enhance ultrasound imaging and show promise for controlled drug delivery and gene transfection. Air entrainment in turbulent ocean waves is critical for carbon sequestering and for the health of ocean ecosystems. Efficiency of boiling heat transfer and many chemical reactions depend upon bubble distribution and interaction with the fluid. Bubbles affect the hydrodynamics of ships and two-phase flow in gas/oil pipelines. Despite the large number of applications that would benefit, our understanding of how bubbles interact with complex fluid flows has significant gaps. A unique three-dimensional ultrasound technique provides observations of bubble behavior in a sequence of three flows: uniformly rotating laminar flow, a turbulent vortex, and fully developed turbulence. In each of these cases, the poorly understood lift forces and history effects influence the motion of the bubble. The lift force plays a role when vorticity is present in the flow and the history effects are due to interactions of the bubble with it's own wake. We study these effects on individual bubbles as well how they manifest in large-scale collective behavior of many bubbles. Connecting the small and large-scale behaviors is the primary goal of this research and is necessary to accurately model and predict bubbly flows in practical applications.