湍流输运的张量系数模型

TENSOR DIFFUSIVITY MODEL OF TURBULENT TRANSFER

关键词:  紊流扩散  紊流模型  紊流传热  紊流

Key words:  Turbulent diffusion  Turbulent model  Turbulence  Turbulence heat transfer

摘要:

实验表明,除均匀各向同性湍流之外,由湍流脉动引起的标量的输运都是各向异性的,且平均量梯度与湍流输运通量之间有一夹角。因此,在用梯度准则模拟湍流输运时,其输运系数应是一个二阶张量。本文推出一个张量形式的输运系数计算公式,并用它分析均匀各向同性湍流、有应变率的均匀剪切流、管内流动和二维平面射流中的热通量问题,均获得了满意的结果。

Abstract:

Experimental data show that the transfer of scalar in turbulent flows is non-isotropic and the turbulent flux is at an angle with the mean scalar gradient in homogeneous isotropic turbulence. So the turbulent diffusiv-ity in gradient transfer model of scalar should be a second order tensor. In this paper a formula of the turbulent diffusivity tensor is derived, then the homogeneous isotropic turbulence, the homogeneous shear turbulence with a mean velocity gradient, the turbulent flux in a circle tube and in two-dimension plane jet are analysed and the results are satisfactory.