Vortex Formation in 2D Fluids X. L. Wu , University of Pittsburgh, DMR-0242284

1. U U Vortex Formation in 2D Fluids X. L. Wu, University of Pittsburgh, DMR-0242284 Vortices are ubiquitous in fluids and can form on scales as small as a fraction of millimeter to as large as hundreds of kilometers. The formation of hurricanes is just one of the extreme examples of large-scale atmosphere manifestation with devastating consequences. We investigate fundamental physics that governs the formation and the evolution of vortices. In the two examples below, a triangular (a) and a circular cylinder (b) are exposed to a uniform velocity, U. They illustrate that, despite entirely different initial configurations, the vortex structure downstream is universal . Our work attempts to establish that this universal structure is no coincidence but obeys the similar laws as in thermodynamics. (a) (b)

2. Vortex Formation in 2D FluidsX. L. Wu, University of PittsburghDMR-0242284 Education: Two undergraduates (Pedram Roushan, Stephen Brenner) and three graduate students (Yonggun Jun, Jie Zhang, and Ayhan Duzgun) have contributed to this project. Pedram was a Goldwater scholar and is now a graduate student at Princeton University. Jie just obtained his Ph.D. degree and is now a postdoctoral fellow at Duke University. Stephen is a student from the Carnegie Mellon University. Because the project fascinated him so much he decided to work in the lab two afternoons a week. Societal Impact: It is hard to underestimate the importance of understanding how vortices behave after hurricane Katrina disaster. The connection between 2D turbulence and formation of large wind structures, such as hurricane and typhoon, makes the current research all the more relevant. We also investigate various means to suppress vortex formation, which may find industrial applications. The project is well suited for training future scientists in this important area of research.