滑移流对浅水湖泊风浪传播特性影响试验研究

Experimental study on the influence of drift flow on the propagation characteristics of wind waves in shallow lakes

浅水湖泊等有限风吹程及水深水域的风浪多处于发展阶段,风拖曳表层水体产生的滑移流会对风浪传播特性产生影响,风浪的波速、波长等参数难以通过线性波的理论频散关系获取。为准确预测湖泊风浪参数,在考虑浅水湖泊的有限吹程和水深特征的基础上,利用风洞水槽模拟研究了滑移流对风浪传播特性的影响。结果表明:滑移流、斯托克斯流及表面流均与风速正相关,滑移流与表面流比值随着风速的增加逐渐降低并稳定于75%;滑移流对波速和波长有促进作用,对小尺度波浪的促进作用尤其显著;波浪非线性会抑制滑移流对波速及波长的促进作用;建立了考虑滑移流影响的风浪经验频散关系式以及风浪主频波速经验关系式。

Wind waves are mostly in the development stage in areas such as shallow lakes and other places with limited wind blowing range and water depth.The surface drift flow generated by wind may affect the propagation characteristics of the wind waves.Wave parameters,such as wave celerity and wavelength,are difficult to be obtained through the dispersion relations of the linear wave theory.To accurately forecast the parameters of the wind wave in shallow lakes,the influence of drift flow on wind wave propagation in a wind tunnel was investigated by considering the characteristics of shallow lake s limited blowing range and water depth.The results showed that the drift flow,stokes flow and surface flow were all positively correlated with the wind speeds.With the increase of wind speed,the ratio of the drift flow to the surface flow gradually decreased and stabilized at the value of 75%.The drift flow could promote the wave celerity and wavelength,especially for small-scale waves.Nonlinearity of waves suppressed the effect of drift flow on the wave celerity and wavelength.The empirical dispersion relation of wind waves and empirical relation of dominant frequency wave celerity,considering the influences of drift flow,are established.