Abstract—

The occurrence of turbulent pulsations in straight pipes of noncircular cross-section leads to the situation, when the average velocity field includes not only the longitudinal component but also transverse components that form a secondary flow. This hydrodynamic phenomenon discovered at the twenties of the last century (J. Nikuradse, L. Prandtl) has been the object of active research to the present day. The intensity of the turbulent secondary flows is not high; usually, it is not greater than 2–3% of the characteristic flow velocity. Nevertheless, their contribution to the processes of transverse transfer of momentum and heat is comparable to that of turbulent pulsations. In this paper, a review of experimental, theoretical, and numerical studies of secondary flows in straight pipes and channels is given. Emphasis is placed on the issues of revealing the physical mechanisms of secondary flow formation and developing the models of the apriori assessment of their forms. The specific features of the secondary flow development in open channels and channels with inhomogeneously rough walls are touched upon. The approaches of semiempirical simulation of turbulent flows in the presence of secondary flows are discussed.

中文翻译：

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普朗特的第二类二次流。描述、预测和模拟问题

摘要-

在非圆形截面的直管中出现湍流脉动会导致这种情况，即平均速度场不仅包括纵向分量，还包括形成二次流的横向分量。这种在上世纪 20 年代发现的流体动力学现象 (J. Nikuradse, L. Prandtl) 一直是当今活跃研究的对象。湍流二次流强度不高；通常不大于特征流速的2-3%。然而，它们对动量和热量的横向传递过程的贡献与湍流脉动的贡献相当。在本文中，对直管和渠道中二次流的实验、理论和数值研究进行了综述。重点放在揭示二次流形成的物理机制和开发其形式的先验评估模型的问题上。涉及明渠和具有不均匀粗糙壁的通道中二次流发展的具体特征。讨论了存在二次流时湍流半经验模拟的方法。