Shear flow turbulence structure and its Lagrangian statistics

摘要: Rapid distortion theory and kinematic simulations are used to investigate the effects of a high shear rate on structure homogeneous turbulence. The results show that an important effect acting initially isotropic turbulence is selective amplification structures having large length scale in mean flow direction, which leads velocity fields contain many large-scale coherent structures. Using simulation, we how streamwise, spanwise vertical integral scales change at different rates. Particular attention given Lagrangian statistics. computations simulation indicate for uniform shear, time all three components TiiL (i = 1, 2 3) proportional Liix/σu, contrast generally assumed estimates T11L ~ L11x/σu, T22L L22y/σν T33L L33z/σw. This consistent with Turfus Hunt (1986) obtained rigid surface blocks fluctuations z 0. Also increases, while decrease, as increases.