On the Comparison of Flow Physics between Minimal and Extended Flow Units in Turbulent Channels
On the Comparison of Flow Physics between Minimal and Extended Flow Units in Turbulent Channels
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DOI：
10.3390/fluids6050192
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发表时间：
2021-05
期刊：
影响因子：
1.9
通讯作者：
Ethan A. Davis;S. Mirfendereski;J. S. Park
中科院分区：
文献类型：
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作者：
Ethan A. Davis;S. Mirfendereski;J. S. Park
在200≤Reτ≤1000范围内，通过直接数值模拟研究了最小流动单元（MFU）的域尺寸及其固有的周期性边界条件对湍流通道流动物理特性的影响。这是通过将湍流统计数据与扩展域模拟的子域（SD）计算结果进行比较来实现的。匹配MFU和SD的尺寸，并设置SD动态以最大限度地减少人为周期性。健康mfu的流向和展向尺寸随雷诺数线性增加。MFU和SD的统计和动态都是健康的，并且很一致。这表明健康的MFU动态可以很好地代表扩展域动态，直至Reτ=1000，表明周期条件对MFU的影响几乎可以忽略不计。然而，在Reτ=200时，MFU在缓冲层内有一个小的偏差，表现为平均速度增加，u ‘ -v ’平面Q2象限有一个尾巴。因此，应该注意的是，在考虑MFU域大小时，可能需要制定更严格的标准来确保健康的湍流动力学。
Direct numerical simulations were performed to study the effects of the domain size of a minimal flow unit (MFU) and its inherent periodic boundary conditions on flow physics of a turbulent channel flow in a range of 200≤Reτ≤1000. This was accomplished by comparing turbulent statistics with those computed in sub-domains (SD) of extended domain simulations. The dimensions of the MFU and SD were matched, and SD dynamics were set to minimize artificial periodicities. Streamwise and spanwise dimensions of healthy MFUs were found to increase linearly with Reynolds number. It was also found that both MFU and SD statistics and dynamics were healthy and in good agreement. This suggests that healthy MFU dynamics represent extended-domain dynamics well up to Reτ=1000, indicating a nearly negligible effect of periodic conditions on MFUs. However, there was a small deviation within the buffer layer for the MFU at Reτ=200, which manifested in an increased mean velocity and a tail in the Q2 quadrant of the u′-v′ plane. Thus, it should be noted that when considering an MFU domain size, stricter criteria may need to be put in place to ensure healthy turbulent dynamics.