We present an investigation into the statistical properties of light traveling through a turbulent medium. Specifically, we analyze the probability density function (PDF) of the light intensity I on a detector for different values of I and the beam path length. The PDF, P(I), exhibits two tails with stretched exponents smaller than one. This indicates a significantly higher probability of rare events with light intensities much greater than the average than would be predicted by a naive Gaussian estimate. We find that these rare events are caused by a randomly located lens in the light path, which allows us to predict the shape of bright spots on the detector.

Biography
Prof. V.V. Lebedev obtained a B.S. in Physics (1974) and an M.S. in Theoretical Physics (1976), both from the Moscow Institute of Physics and Technology. Later, he received his PhD in Theoretical Physics (1979) from the Landau Institute for Theoretical Physics. He has been a Corresponding Member of the Russian Academy of Sciences since 2003, a Chair Professor at the Moscow Institute of Physics and Technology since 2008, and a Principal Researcher at the Landau Institute for Theoretical Physics since 2019. He served as Director of the Landau Institute for Theoretical Physics (2003-2018). He has over 150 scientific publications, with research focusing on the theory of soft condensed matter, the theory of nonequilibrium dynamical phenomena (including turbulence), statistical theory, and theoretical biophysics.

This talk elucidates the vortex-dominated flows and unsteady lift underpinning the high-performance flight of bats—the only mammals capable of active flapping flight. A key kinematic feature examined is the dynamic wingspan variation observed during flapping flight. Based on numerical simulations of flows over a slow-flying bat, it is found that the dynamically changing wingspan can significantly enhance the lift. Analysis of the resultant vortex structures and a decomposition of aerodynamic forces show that the enhancement is primarily attributable to an intensified leading-edge vortex system, whose strength is promoted by the dynamic wing morphing. A quantitative lift formulation developed for unsteady aerodynamic analysis under these conditions will also be presented.

Biography
Prof. Shi-Zhao Wang received his doctoral degree in fluid dynamics from University of Chinese Academy of Sciences in 2011. He is currently a professor at Institute of Mechanics, Chinese Academy of Sciences. His research focuses on unsteady aerodynamics, aeroacoustics, and biolocomotion. He has authored more than 90 peer reviewed papers in leading journals in fluid mechanics, including Annual Review of Fluid Mechanics, Journal of Fluid Mechanics, and Physical Review Fluids.