线性密度分层流体中半球体运动生成内波的实验研究

在密度线性分布的分层流试验水槽中,对贴近侧壁面的半球体模型运动生成的内波进行了实验研究. 采用多通道电导率阵列,测量分析了拖曳模型产生内波的波形结构、垂向位移场及其相关速度等. 实验结果表明:半球体模型产生的内波可以分为两类,一类是由定常源激发的体积效应内波,另一类是由非定常源激发的尾迹内波,由前者转换为后者的临界内Froude(Fr)数是Fr_s =1.6;与球体模型实验比较,Fr_s约为球体的2/3,转换更迅速,界线更清 关键词： 分层流 半球模型 内波 尾迹

Experiments on the generation of internal waves by a hemispheroid in a linearly stratified fluid

Experiments are conducted to examine the characteristics of internal waves generated by a towing hemispheroid model alongside the side wall of stratified fluid flume with a linear density distribution. By the measured results with multi-channel conductivity arrays, the wave patterns, the vertical displacement and the correlation velocity for such internal waves are analyzed. Two distinct types of internal waves are obtained in experiments. One is the body-generated internal wave by the steady source with respect to the hemispheroid model, and the other is the wake-generated internal wave by the unsteady source. The transition between these two types of internal waves occurs at a critical Froude number of Fr_S=1.6. The corresponding comparison with towing spheroid model experiments is carried out. It follows that the number Fr_S is about 2/3 that of the spheroid and that the transition is more rapid and its borderline is more clear-cut than those of the spheroid modes. The body-generated internal waves of both experimental models have identical characteristics, but the draining-water volume is about 2/3 that of the spheroid model. Their wake-generated internal waves possess similar variation tendencyies, but their wave speed is about 2/3 that of the spheroid model . It also proves that this mirror-image experimental method in the flume can increase the effective range of spatio-temporal evolvement of body-generated internal waves.