摘要
被动分级的问题的一个壳模型版本被介绍,它被 K 的模型启发。Ohkitani 和 M。Yakhot [K。Ohkitani 和 M。Yakhot, Phys。加快。Lett。60 (1988 ) 983;K。Ohkitani 和 M。Yakhot,学监。Theor。Phys。81 (1988 ) 329 ] 。作为处于原来的问题,规定随机的速度地是 Gaussian, δ
及时相关。确定的微分方程被认为是非线性的 Langevin 方程。然后,为被动数量的 PDF 的佛克普朗克常数方程数字地被获得并且解决。在精力输入范围(n 【
5, n 是壳数字) ,被动数量的概率分发功能(PDF ) 在 Gaussian 分发附近。在惯性的范围(5 ≤
n ≤
16 ) 并且驱散范围(n ≥
17 ) ,被动数量的概率分发功能(PDF ) 有明显的间歇性。并且被动数量的可伸缩的力量是异常的。数字模拟的结果与试验性的大小相比。
A shell-model version of passive scalar problem is introduced, which is inspired by the model of K. Ohkitani and M. Yakhot [K. Ohkitani and M. Yakhot, Phys. Rev. Lett. 60 (1988) 983; K. Ohkitani and M. Yakhot, Prog. Theor. Phys. 81 (1988) 329]. As in the original problem, the prescribed random velocity field is Gaussian and 5 correlated in time. Deterministic differential equations are regarded as nonlinear Langevin equation. Then, the Fokker-Planck equations of PDF for passive scalars are obtained and solved numerically. In energy input range (n 〈 5, n is the shell number.), the probability distribution function (PDF) of passive scalars is near the Gaussian distribution. In inertial range (5≤ n ≤ 16) and dissipation range (n ≥ 17), the probability distribution function (PDF) of passive scalars has obvious intermittence. And the scaling power of passive scalar is anomalous. The results of numerical simulations are compared with experimental measurements.
基金
The project supported by National Natural Science Foundation for Major Projects under Grant Nos.10336010 and 10576005
关键词
壳模型
分布函数
PDF
物理研究
shell model, passive scalar, distribution function