报告题目：Fluctuations of passive scalar convected by homogeneous turbulence
报告人：Toshiyuki Gotoh 教授（日本名古屋工业大学）
报告摘要：One of properties of turbulence lies in its huge transport power of mass, momentum and energy, and in their large and violent fluctuations of these quantities. A scalar which is convected by turbulence without reaction to the fluid is passive scalar and has long been studied in many ways partly because the transport equation is linear while sharing the convection and molecular diffusion with those of the velocity. However, the scalar equation is statistically nonlinear. It is now well known that the passive scalar fluctuations at small scales are more intermittent than the velocity and the statistics may not be universal. In the lecture the spectrum of the scalar variance at high Schmidt number is argued from the view points of the spectral theory and the velocity intermittency. Also the scaling exponents of the moments of the scalar increment with Schmidt number of order unity are discussed by using the direct numerical simulation.