垂直自由降膜流表面波的非线性演化　

Nonlinear Evolution of Surface Waves for Vertically Free Falling Films

借助自行研制并经改进的多点电导传感器和微机化实时在线测量系统，对垂直管外自由降膜流表面波的演化进行实时在线测量。结果表明，表面波的演化具有显著的非线性特性，其波形不仅与纵向距离和时间有关，而且还与液膜雷诺数有极大关系；此外，表面波的形态及其演化还对初始扰动比较敏感。根据测量结果估算了与数值模拟有关的波速。

The evolution of surface waves is measured for vertically free falling films using the improved microcomputer-based on-line and real-time measurement system. It reveals that the evolution of surface waves present remarkable nonlinear behavior. The surface wave shape is not only dependent on longitudinal distance and time, but also strongly related to the film Reynolds number. Moreover, the shape and evolution are sensitive to initial disturbance. The celerity for numerical simulation is estimated according to measureing results.