Lepreti Fabio, Carbone Vincenzo, Veltri Pierluigi
Dipartimento di Fisica, Università della Calabria, Via P. Bucci 31/C, I-87036 Rende (CS), Italy.
Phys Rev E Stat Nonlin Soft Matter Phys. 2006 Aug;74(2 Pt 2):026306. doi: 10.1103/PhysRevE.74.026306. Epub 2006 Aug 25.
Modeling the intermittent behavior of turbulent energy dissipation processes in both space and time is often a relevant problem when dealing with phenomena occurring in high-Reynolds-number flows, especially in astrophysical and space fluids. In this paper, a dynamical model is proposed to describe the intermittency of the energy dissipation rate in a turbulent system. This is done by using a shell model to simulate the time evolution of the turbulent cascade and introducing some heuristic rules, partly inspired by the well-known p model, to construct a spatial structure of the energy dissipation rate. In order to validate the model and to study its spatial intermittency properties, a series of numerical simulations have been performed. These show that the level of spatial intermittency of the system can be simply tuned by varying a single parameter of the model and that scaling laws in agreement with those obtained from experiments on fully turbulent hydrodynamic flows can be recovered. It is finally suggested that the model could represent a useful tool to simulate the intermittent structure of turbulent energy dissipation in those high-Reynolds-number astrophysical fluids where impulsive energy release processes can be associated with the dynamics of the turbulent cascade.
在处理高雷诺数流动中出现的现象时，尤其是在天体物理和空间流体中，对湍流能量耗散过程在空间和时间上的间歇性行为进行建模往往是一个相关问题。本文提出了一个动力学模型来描述湍流系统中能量耗散率的间歇性。这是通过使用壳模型来模拟湍流级联的时间演化，并引入一些启发式规则（部分灵感来自著名的p模型）来构建能量耗散率的空间结构来实现的。为了验证该模型并研究其空间间歇性特性，进行了一系列数值模拟。这些模拟表明，通过改变模型的单个参数可以简单地调整系统的空间间歇性水平，并且可以恢复与完全湍流流体动力学流动实验中获得的标度律一致的标度律。最后有人提出，该模型可能是一个有用的工具，可用于模拟那些高雷诺数天体物理流体中湍流能量耗散的间歇性结构，在这些流体中，脉冲能量释放过程可能与湍流级联的动力学相关。
