Spectral turbulence kinetic energy budget and scale-based velocity decomposition for turbulence in bubble plumes
Spectral turbulence kinetic energy budget and scale-based velocity decomposition for turbulence in bubble plumes
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DOI：
10.1063/5.0151046
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发表时间：
2023-06
影响因子：
4.6
通讯作者：
Huijie Wu;Binbin Wang
中科院分区：
文献类型：
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作者：
Huijie Wu;Binbin Wang
我们进行了光谱分析的湍流动能（TKE）预算中的气泡羽流使用粒子图像测速与荧光粒子。我们的研究结果证实了一个反向的能量级联的气泡羽流，其中TKE是从小到大的漩涡转移的假设。这是由于直接注入的TKE气泡通道在很宽的尺度范围内，在大尺度的TKE典型的剪切生产相反。湍流耗散被确定为气泡产生的TKE的主要汇，并发生在所有尺度。使用尺度间能量传递的临界长度尺度的速度分解使我们能够区分大尺度和小尺度的气泡羽流运动。大尺度湍流脉动呈现出偏态分布，可能与气泡通过后的回流和气泡尾迹诱导的速度有关。小尺度湍流脉动较好地服从高斯分布。大尺度运动对雷诺应力的贡献超过一半，而小尺度运动对羽流中心附近的法向应力有显著的贡献，但对切应力没有贡献。涡度场中的大尺度运动诱导了垂直伸长的涡对，而小尺度涡在水平和垂直方向上都表现出相似的尺寸。
We conducted a spectral analysis of the turbulence kinetic energy (TKE) budget in a bubble plume using particle image velocimetry with fluorescent particles. Our findings confirmed the hypothesis of an inverse energy cascade in the bubble plume, where TKE is transferred from small to large eddies. This is attributed to direct injection of TKE by bubble passages across a wide range of scales, in contrast to canonical shear production of TKE in large scales. Turbulence dissipation was identified as the primary sink of the bubble-produced TKE and occurred at all scales. The decomposition of velocities using the critical length scale of inter-scale energy transfer allowed us to distinguish between large- and small-scale motions in the bubble plume. The large-scale turbulent fluctuations exhibited a skewed distribution and were likely associated with the return flow after bubble passage and the velocities induced by the bubble wake. The small-scale turbulent fluctuations followed a Gaussian distribution relatively well. The large-scale motions contributed to over half of the Reynolds stresses, while there were significant small-scale contributions to the normal stresses near the plume center but not to the shear stress. The large-scale motions in the vorticity field induced a street of vertically elongated vortex pairs, while the small-scale vortices exhibited similar sizes in both horizontal and vertical directions.