题 目：On Kinetic Theory Representation of Averaged Dynamics of Turbulence
报告人：陈沪东 浙江大学
时间：2025年5月30日星期五下午13:30
地点：上海大学延长校区力学所200学术报告厅
专家简介
陈沪东，美国国家工程院院士（2023）和美国物理学会会士（2000）。本科毕业于复旦大学，后经李政道组织的CUSPEA赴美留学，获威廉玛丽学院硕士、达特茅斯学院博士学位，并在洛斯阿拉莫斯国家实验室完成博士后研究。曾担任达索系统公司流体首席科学官，是格子玻尔兹曼方法的开创者和关键发展者，在计算流体力学、统计物理学、动力学理论、湍流和复杂流体理论与建模、数值方法等方面拥有30多年的工作经验，创建了国际知名的通用流体模拟工业软件PowerFLOW。现任浙江大学能源工程学院教授。
摘要信息
The mean dynamics for inhomogeneous turbulence can be described by a proper kinetic equation for one-point pdf constructed from the first principles by averaging the Klimontovich-type equation for fluid elements satisfying exactly the Navier-Stokes hydrodynamics. The turbulent kinetic energy plays a role of temperature as in standard molecular thermodynamics. The Reynolds stress tensor as well as any higher (or lower) order one-point moments can be directly obtained from the moment integration of the one-point pdf. It is shown that dynamics of turbulent fluctuations resemble a collision process that drives the mean distribution towards a Gaussian (Maxwell Boltzmann) equilibrium form asymptotically. Non-Gaussianity in this framework is a direct result of non-equilibrium effects due to inhomogeneity of the flow. Due to lack of separation between the mean and the fluctuating scales, the mean turbulent flow is not in general describable by a Navier-Stokes equation with an eddy viscous term. Instead, an averaged turbulent flow behaves more like a flow of a finite Knudsen number containing effects beyond the linear non-equilibrium order, and thus is more suitably described in a kinetic theoretic representation. The collision term due to fluctuation of turbulence may be modeled by a single-time relaxation process with the relaxation time estimated from a fluctuation-dissipation relationship. The whole representation of the mean dynamics of inhomogeneous turbulence is thus closed.
