Dávila J, Vassilicos J C
E. Superior de Ingenieros, Camino de los Descubrimientos s/n, 41092-Sevilla, Spain.
Phys Rev Lett. 2003 Oct 3;91(14):144501. doi: 10.1103/PhysRevLett.91.144501.
DNS and laboratory experiments show that the spatial distribution of straining stagnation points in homogeneous isotropic 3D turbulence has a fractal structure with dimension D(s)=2. In kinematic simulations the exponent gamma in Richardson's law and the fractal dimension D(s) are related by gamma=6/D(s). The Richardson constant is found to be an increasing function of the number density of straining stagnation points in agreement with pair diffusion occurring in bursts when pairs meet such points in the flow.
DNS 和实验室实验表明，均匀各向同性三维湍流中应变停滞点的空间分布具有分形结构，其维度 D(s)=2。在运动学模拟中，理查森定律中的指数γ与分形维数 D(s) 的关系为γ=6/D(s)。研究发现，理查森常数是应变停滞点数量密度的增函数，这与流动中粒子对遇到此类点时突发的对扩散现象相符。
