Front propagation and critical gradient transport models
Front propagation and critical gradient transport models
复制标题
DOI：
10.1063/1.2824375
复制
发表时间：
2007-12-01
影响因子：
2.2
通讯作者：
Diamond, P. H.
中科院分区：
文献类型：
--
作者：
Garbet, X.;Sarazin, Y.;Diamond, P. H.
本文分析了将热方程耦合到湍流强度演化方程的双场临界梯度模型的性质。结果表明，微扰的动力学是弹道的或扩散的，这取决于脉冲的形状和温度梯度到不稳定性阈值的距离。这种双重性体现在该模型对波包的线性响应中。在研究该系统的非线性解时得到了恢复。自相似扩散锋面和弹道锋面都存在。当传播为弹道时，前锋速度是湍流扩散系数和微不稳定性增长率之间的几何平均值。(C)2007年美国物理研究所。
This paper analyzes the properties of a two-field critical gradient model that couples a heat equation to an evolution equation for the turbulence intensity. It is shown that the dynamics of a perturbation is ballistic or diffusive depending on the shape of the pulse and also on the distance of the temperature gradient to the instability threshold. This dual character appears in the linear response of this model for a wave packet. It is recovered when investigating the nonlinear solutions of this system. Both self-similar diffusive fronts and ballistic fronts are shown to exist. When the propagation is ballistic, it is found that the front velocity is the geometric mean between the turbulent diffusion coefficient and a microinstability growth rate. (C) 2007 American Institute of Physics.