充分发展的湍流通道流动耗散单元的层析粒子成像测速研究

A new method to describe statistical information from passive scalar fields has been proposed by
Wang and Peters The length-scale distribution function of the distance between extremal points in
passive scalar turbulence, J. Fluid Mech. 554, 457 2006. They used direct numerical simulations
DNS of homogeneous shear flow to introduce the innovative concept. This novel method
determines the local minimum and maximum points of the fluctuating scalar field via gradient
trajectories, starting from every grid point in the direction of the steepest ascending and descending
scalar gradients. Relying on gradient trajectories, a dissipation element is defined as the region of all
the grid points, the trajectories of which share the same pair of maximum and minimum points. The
procedure has also been successfully applied to various DNS fields of homogeneous shear
turbulence using the three velocity components and the kinetic energy as scalar fields L. Wang and
N. Peters, Length-scale distribution functions and conditional means for various fields in
turbulence, J. Fluid Mech. 608, 113 2008. 德国LaVision PIV/PLIF粒子成像测速场仪 体视层析粒子成像测速系统(Tomo-PIV) 自适应粒子成像测速场仪（PIV）