Generation of internal gravity waves by an oscillating horizontal disc
Generation of internal gravity waves by an oscillating horizontal disc
复制标题
通过水平振荡圆盘产生内部重力波
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Stefan G. Llewellyn Smith
中科院分区：
文献类型：
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作者：
P. Martin;Stefan G. Llewellyn Smith
内部重力波是通过水平盘的任意受迫振动在分层流体中产生的。波场在时域和频域中计算。在时域中，使用拉普拉斯变换解决初值问题；因果关系是强加的。在频域（时谐振荡）中，施加辐射条件：使用平面波（傅立叶）分解，其中选择具有传出群速度的波。结果表明，一旦忽略瞬态效应，两种方法都会得到相同的解决方案。然后，给出了一种使用二重积分渐近近似计算远场的方法。结果表明，对于圆盘的任意力，总能量通量是向外的。对能量传输进行了进一步的研究，以澄清频域中辐射条件的性质。
Internal gravity waves are generated in a stratified fluid by arbitrary forced oscillations of a horizontal disc. The wave fields are calculated in both the time domain and the frequency domain. In the time domain, an initial-value problem is solved using Laplace transforms; causality is imposed. In the frequency domain (time-harmonic oscillations), a radiation condition is imposed: a plane-wave (Fourier) decomposition is used in which waves with outgoing group velocity are selected. It is shown that both approaches lead to the same solution, once transient effects are ignored. Then, a method is given for calculating the far-field, using asymptotic approximations of double integrals. It is shown that the total energy flux is outwards, for arbitrary forcings of the disc. Further investigations of energy transport are made with a view to clarifying the nature of radiation conditions in the frequency domain.