Turbulent mixing of passive scalar near turbulent and non-turbulent interface in mixing layers
Turbulent mixing of passive scalar near turbulent and non-turbulent interface in mixing layers
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DOI：
10.1063/1.4928199
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发表时间：
2015-08
影响因子：
4.6
通讯作者：
Tomoaki Watanabe;Y. Sakai;K. Nagata;Yasumasa Ito;T. Hayase
中科院分区：
文献类型：
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作者：
Tomoaki Watanabe;Y. Sakai;K. Nagata;Yasumasa Ito;T. Hayase
对不同的施密特数（Sc = 0.25，1，4和8）进行了时间上发展的被动标量输运混合层的直接数值模拟。本文研究了湍流/非湍流界面（TNTI）附近的湍流混合，TNTI是由湍流子层（TSL）和粘性上层（VSL）组成的一个层。无旋边界靠近TNTI层外缘，被检测为小涡度等值面。分析了流体元相对于无旋边界运动的运动。一旦非湍流流体被涡量的粘性扩散穿过无旋边界夹带到VSL中，流体在无旋边界的法线方向上远离VSL中的无旋边界。流体到达TSL后，沿无旋边界的切向输送，并与来自湍流核心区的流体混合。The boundary between the…
A direct numerical simulation of a temporally developing mixing layer with a passive scalar transport is performed for various Schmidt numbers (Sc = 0.25, 1, 4, and 8). Turbulent mixing is investigated near the turbulent/non-turbulent interface (TNTI), which is a layer consisting of the turbulent sublayer (TSL) and viscous superlayer (VSL). The irrotational boundary, which is close to the outer edge of the TNTI layer, is detected as the isosurface of small vorticity magnitude. The movement of fluid elements relative to the irrotational boundary movement is analyzed. Once the non-turbulent fluid is entrained into the VSL across the irrotational boundary by the viscous diffusion of vorticity, the fluid moves away from the irrotational boundary in the VSL in the normal direction of the irrotational boundary. After the fluid reaches the TSL, it is transported in the tangential direction of the irrotational boundary and is mixed with the fluid coming from the turbulent core (TC) region. The boundary between th...