河流床面总是伴随有一定的形态, 如沙纹或沙垄等. 即使原始理想的平整床面, 并保持水流运动的层流状态, 在流动开始后不久, 由于外界的扰动作用, 层流失稳, 床面也会出现沙纹. 而沙纹的出现, 又将进一步改变原始平整床面层流失稳的轨迹. 床面沙纹的波状特征, 将诱发明渠层流新的不稳定性, 与平整床面层流失稳相比, 两者存在本质的区别, 其稳定中性曲线前移, 失稳临界Reynolds数降低, 流动失稳过程中, 对扰动波数的响应范围加大, 层流失稳更容易发生. 沙纹移动频率也会对流动失稳产生较大的影响, 动床明流失稳与定床明流失稳有很大差别, 对此也做了研究. River bed is always accompanied by a certain shape, such as sand grain or sand dune, etc. Even if the original ideal flat bed, and to maintain the laminar flow of water flow state, shortly after the start of the flow, due to disturbance outside the role of layer loss Stable, bed will appear sand grain, and the appearance of sand grain, will further change the original formation of flat bed steady flow trajectory. Bed corrugated characteristics of sand will induce new instability of open channel laminar flow, and There is an essential difference between the two. The stable neutral curve moves forward and the critical Reynolds number of instability decreases. In the process of flow instability, the response range to disturbance wave number increases, and the laminar flow instability changes more Easy to occur.The frequency of sand grain movement will also have a greater impact on the flow instability, dynamic bed Mingliu destabilization and fixed bed Mingliu instability are very different, this has also been studied.