Mixing characteristics of an inhomogeneous scalar in isotropic and homogeneous sheared turbulence
Mixing characteristics of an inhomogeneous scalar in isotropic and homogeneous sheared turbulence
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各向同性和均匀剪切湍流中非均匀标量的混合特性
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
S. Elghobashi
中科院分区：
文献类型：
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作者：
K. Nomura;S. Elghobashi
在非预混反应流的背景下研究了非均匀被动标量场的湍流混合。对均匀剪切湍流作用下的初始阶梯标量场进行了直接数值模拟，并将结果与衰减各向同性湍流的情况进行了比较。对于这两种流动条件，守恒标量的梯度倾向于与最大压缩应变率的轴对齐并且与局部涡度正交。标量梯度的大小直接受局部应变率影响，而其方向则受局部涡度控制。由于剪切湍流的方向特征，标量梯度的方向比各向同性湍流更加有序。此外，涡量的大小通过涡旋拉伸的应变率放大间接影响标量梯度的大小。在这两种流动中，高标量梯度幅度或标量耗散的区域（以及......
Turbulent mixing of an inhomogeneous passive scalar field is studied in the context of a nonpremixed reacting flow. Direct numerical simulations of an initial steplike scalar field subjected to homogeneous sheared turbulence have been performed and the results compared with those of the case of decaying isotropic turbulence. For both flow conditions, the gradient of the conserved scalar tends to align itself with the axis of the most compressive strain rate and orthogonal to the local vorticity. The magnitude of the scalar gradient is directly influenced by the local strain rate while its orientation is controlled by the local vorticity. Because of the directional features of sheared turbulence, the orientation of the scalar gradient is more ordered than in isotropic turbulence. In addition, the magnitude of vorticity indirectly affects that of the scalar gradient through strain‐rate amplification by vortex stretching. In both flows, regions of high scalar‐gradient magnitude or scalar dissipation (and the...