Abstract:

Turbulence is inherently a multiscale phenomenon, in which nonlinear cascades redistribute energy across scales and govern key flow characteristics, including dissipation, scalar mixing, and dispersion. It is well known that the forward cascade is dominant in three-dimensional turbulence, i.e., energy is transferred from large scales to smaller scales, where it is ultimately dissipated into heat due to viscosity. Recent studies, however, have shown that inverse energy transfer (backscatter), also occurs and may be more frequent and dynamically important than traditionally expected. In this talk, I will present recent work on inverse cascades, focusing on their relationship with local flow deformation, local dissipation, and possible connections to non-equilibrium thermodynamics.

Introduction of speaker:

Dr. Hanxun Yao is an Assistant Professor in the Department of Modern Mechanics at USTC (Heifei, China). He received his Bachelor, MPhil and PhD degrees from the Ocean University of China, University of Sydney and Imperial College London in Physics, Computational Fluid Dynamics and Turbulence. From 2022 to 2025, he worked as a Postdoctoral Fellow at Johns Hopkins University, where he focused on turbulence theory and development of the Johns Hopkins Turbulence Databases (JHTDB). His research group works on turbulence theory (energy cascade, multiscale dynamics, intermittency, nonequilibrium thermodynamics) and turbulence modelling from fundamental (homogenous isotropic turbulence, transitional boundary layer, channel flow) to environmental flows (2D turbulence, Rayleigh-Bénard convection, atmospheric boundary layers, magnetohydrodynamics).

审核：刘有晟、游小清