摘要
通过实验研究了受气流剪切但无明显波动的水气界面下的湍流特性。当界面剪切较强(uτ≥0.20cm/s)时,水面边界层中平均流速、速度脉动强度和Reynolds切应力的分布形状与固壁湍流相似,预示剪切水气界面和固壁附近的湍流相干结构是相类似的。另一方面,水面湍流也表现出不同于固壁湍流的细节特征。与自由面湍流不同的是,在靠近剪切水气界面的流场中流向和垂向速度脉动同时受到抑制。
Measurements of mean velocity and turbulent quantities are carried out under sheared air-water interfaces. Surface shear was imposed by an airflow over the water flow which was kept free from surface waves. Results indicate that, when the shearing airflow is relatively strong (interface friction velocity on water side μτ greater than or equal 0.20 cm/s), distributions of mean velocity, turbulence intensities and Reynolds shear stress near the water surface are similar to those observed in near-wall turbulence, suggesting the similarity of turbulent coherent structures in the two flows. On the other hand, the present data also show some characteristics peculiar to sheared air-water interfaces. In the flow field close to sheared air-water interfaces, velocity fluctuations both in streamwise and in vertical directions are damped. This is a notable feature that distinguishes turbulence near sheared air-water interface and free-surface turbulence.
出处
《流体力学实验与测量》
EI
CSCD
北大核心
2004年第2期86-90,共5页
Experiments and Measurements in Fluid Mechanics
基金
国家自然科学基金(19672070资助项目)
