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将弯曲河流中湍流结构看做一种扰动波,通过分析扰动波增长率的变化来研究湍流结构的动力演化特征.针对二维弯曲河流,采用流动稳定性理论与摄动法建立河流自然坐标下的湍流运动理论模式,运用差分法离散方程,利用Muller法进行特征值求解,进而分析弯曲河道二维湍流结构在不同弯曲度和雷诺数条件下的变化.结果表明,湍动能量主要由小尺度涡体结构产生的脉动来提供,小尺度涡体结构的演变比较剧烈,对河道弯曲度和雷诺数的改变也更敏感.另外,弯曲河道对拟序波有一定的选择性,也正是这些特征波的湍流结构促成了弯道的形成及保持.
The turbulent structure in curved river is regarded as a kind of disturbing wave, and the dynamic evolution of turbulent structure is studied by analyzing the variation of the growth rate of turbulence.For the two-dimensional curved river, the flow stability theory and perturbation method are used to establish the natural evolution of the river The turbulence model of turbulent flow in curved channel is analyzed by using the discrete method of difference method and the Muller method to solve the eigenvalue. The results show that the turbulent energy mainly consists of small-scale The eddy structure produces pulsations, and the evolution of small-scale scrolls is dramatic, which is also more sensitive to changes in river curvature and Reynolds number. In addition, curved channels have some selectivity to the waveforms, and it is exactly these The turbulent structure of the eigenvalue contributes to the formation and maintenance of the bend.