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科学通报  2012 

密度分层流体中不同长径比拖曳潜体激发内波特性实验

DOI: 10.1360/972011-1361, PP. 606-617

Keywords: 分层流体,拖曳潜体,Lee,,拟Lee,,湍流尾迹

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Abstract:

在具有连续密度跃层的分层流体中,针对3种不同长径比拖曳潜体激发内波的运动学与动力学特性进行了系列实验.从拖曳潜体产生扰动密度场的动态时间序列测量结果入手,表明体积效应激发内波属于一种相对于拖曳潜体定常的多模态Lee波结构,而尾迹效应激发主控内波为相对于拖曳潜体非定常的拟Lee波结构,这是一类由湍流尾迹中大尺度相干结构作为移动源激发的内波结构.研究表明,在Lee波与拟Lee波之间存在一个与长径比近似为线性关系的临界转捩Froude数Frc,而且转捩后拟Lee波相关速度相应Froude数近似为一个常数0.8.研究进一步表明,存在一个与长径比近似为线性关系的Froude数Frp,当FrFrp时,Lee波为主控内波,无因次内波峰-峰幅值随Fr增大而增大;当FrpFrFrc时,虽然Lee波仍为主控内波,但无因次内波峰-峰幅值随Fr增大而减小,而拟Lee波的影响逐渐增大;当Fr>Frc时,拟Lee波为主控内波,无因次内波峰-峰幅值随Fr增大近似线性增大,而且长径比的影响可以忽略,其中Fr为拖曳潜体特征直径Froude数.

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