The Multi-process and Multi-scale Properties of Hypersonic Turbulent Boundary Layer

Abstract

In recent years, the study of high-speed flows has attracted significant interest from both engineering and academic perspectives, making the understanding of the underlying physics a continuing challenge. In this seminar, the multi-process and multi-scale characteristics of the hypersonic turbulent boundary layer are examined. The underlying mechanisms responsible for the overshoot phenomena observed in mean skin-friction and heat-transfercoefficients are elucidated from a statistical standpoint. The compressibility effect in the near-wall region is investigated using the Helmholtz decomposition. Furthermore, the influence of wall temperature on the inter-scale transfer of kinetic energy is also explored. Building on physical prior knowledge of compressible wall-bounded turbulence, we propose artificial-neural-network-based nonlinear algebraic subgrid-scale models for large-eddy simulation of such flows. The proposed model demonstrates superior performance compared to traditional subgrid-scale models in untrained compressible turbulent channel flow and boundary layer.

Speaker

Dr Dehao Xu received his PhD from Peking University in 2023. He subsequently served as a Postdoctoral Fellow in the Physics of Fluids Group at the University of Twente from 2023 to 2025. He is currently a Postdoctoral Fellow at The Hong Kong Polytechnic University. His research focuses on compressible wall-bounded turbulence and multiphase flows with phase change. He has published more than ten papers as first or corresponding author in leading journals, including Journal of Fluid Mechanics, Physical Review Fluids, and Physics of Fluids.