Boffetta G, Sokolov I M
Dipartimento di Fisica Generale and INFM, Università di Torino, Via Pietro Giuria 1, I-10125 Turin, Italy.
Phys Rev Lett. 2002 Mar 4;88(9):094501. doi: 10.1103/PhysRevLett.88.094501. Epub 2002 Feb 13.
Relative dispersion in fully developed turbulence is investigated by means of direct numerical simulations. Lagrangian statistics is found to be compatible with Richardson description although small systematic deviations are found. The value of the Richardson constant is estimated as C2 approximately equal to 0.55, in a close agreement with recent experimental findings [S. Ott and J. Mann, J. Fluid Mech. 422, 207 (2000)]. By means of exit-time statistics it is shown that the deviations from Richardson's law are a consequence of Eulerian intermittency. The measured Lagrangian scaling exponents require a set of Eulerian structure function exponents zeta(p) which are remarkably close to standard ones known for fully developed turbulence.
通过直接数值模拟研究了充分发展湍流中的相对扩散。尽管发现了小的系统偏差，但拉格朗日统计结果与理查森描述相符。理查森常数的值估计为(C_2\approx0.55)，这与最近的实验结果[S. Ott和J. Mann，《流体力学杂志》422, 207 (2000)]非常一致。通过出射时间统计表明，与理查森定律的偏差是欧拉间歇性的结果。测量得到的拉格朗日标度指数需要一组欧拉结构函数指数(\zeta(p))，它们与充分发展湍流中已知的标准指数非常接近。
