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 byWang and Peters “The length-scale distribution function of the distance between extremal points inpassive scalar turbulence,” J. Fluid Mech. 554, 457 2006. They used direct numerical simulationsDNS of homogeneous shear flow to introduce the innovative concept. This novel methoddetermines the local minimum and maximum points of the fluctuating scalar field via gradienttrajectories, starting from every grid point in the direction of the steepest ascending and descendingscalar gradients. Relying on gradient trajectories, a dissipation element is defined as the region of allthe grid points, the trajectories of which share the same pair of maximum and minimum points. Theprocedure has also been successfully applied to various DNS fields of homogeneous shearturbulence using the three velocity components and the kinetic energy as scalar fields L. Wang andN. Peters, “Length-scale distribution functions and conditional means for various fields inturbulence,” J. Fluid Mech. 608, 113 2008.