简介（Abstract）：Space-time correlations are the simplest but fundamental measurement of turbulent fluctuations in both space and time. Their models provide the indispensable time scales for turbulence statistical theories and are used to transform temporal signals to spatial ones in experiments. The well-known model for space-time correlations is Taylor’s frozen-flow model. However, it suffers from many limitations such as weak shear rates and low turbulence intensity. In this talk, I will systematically present our work on space-time correlations: (1) The EA model is firstly introduced for turbulent shear flows. This model is a second-order approximation to space-time correlation, while Taylor’s model is a first-order one. It is verified by the DNS of turbulent channel flows and used to calculate the spatial spectra from temporal ones. (2) The swept-wave model is further introduced for compressible turbulence. This model is the extension of the linear-wave propagation model originally developed by Lee, Lele and Moin. It is used in the EDQNM approach to derive the scaling of energy spectra.  Finally, I will briefly discuss the space-time correlation approach for time-accurate large eddy simulation of turbulence generated noise and particle-laden turbulence.
 
报告人介绍（Brief Biography）：Dr. He’s research interests include turbulence statistical theory, computational modeling, and large-eddy simulation. He received the “Distinguished Young Scientist Award” from Chinese National Natural Science Foundation in 2004. He is a member of the editorial advisory committee of AIP journal “Physics of Fluids” and serves as associate editors for journals “Acta Mech. Sinica” and “Theoretical and Applied Mechanics Letters”.  He is elected as a fellow of American Physical Society in 2015.