拖曳球体尾流效应内波表现特征及其产生机理研究

采用PIV技术对分层流体中拖曳球体尾流及内波的流场进行了测量,捕捉到了清晰的尾流效应内波的流场图像。尾流效应内波不规则,有一定的随机性,迟于模型出现,呈"V"字形,波长较短,且不随内傅氏数明显变化,与体效应内波特征差异明显。通过对尾流激发内波过程的分析,发现尾流效应内波与尾涡结构紧密相关,试验测量的内波波长与St数决定的涡间距吻合,验证了尾涡激发内波是尾流效应产生内波的一种机制。

Research on the character of wake-generated internal waves by towing sphere and its produced mechanism

Wake flow and internal waves generated by towing sphere in stratified fluids tank are measured using PIV technique.The vivid flow field image of wake-generated internal waves is captured.Wake-generated internal waves are irregular and random waves.They appear late for towing body itself.Their configurations are the shape of'V'.The wavelength is short and is not changed with internal Froude number.The character of wake-generated internal waves is distinctly different from body-generated internal waves.According to the process of wake flow motivated internal waves,it is found that the wake-generated internal waves are related to wake vertex structure.Measurement wavelength is agreed with the vertex spacing determined by Strouhal number.It is validated that wake vertex generated internal waves is one of the mechanisms of wake-generated internal waves.