A comparison of frequency downshift models of wave trains on deep water
A comparison of frequency downshift models of wave trains on deep water
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DOI：
10.1063/1.5063016
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发表时间：
2018-09
影响因子：
4.6
通讯作者：
J. Carter;D. Henderson;Isabelle Butterfield
中科院分区：
文献类型：
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作者：
J. Carter;D. Henderson;Isabelle Butterfield
当波浪沿着水槽或穿过海洋时，频率测量值（通常是频谱峰值或频谱平均值）下降时，深水波列中的频率下降（FD）就会发生。许多FD模型依赖于风或波浪的破碎。我们考虑了七个不包括这些影响的模型，并将它们的预测与同样不包括这些影响的四组实验进行比较。这些模型是(i)非线性薛定谔方程（NLS）， （ii）耗散NLS方程（dNLS）， （iii） dythe方程，（iv）粘性dythe方程（vDysthe）， (v) Gordon方程（Gordon）（有自由参数），（vi） Islas-Schober方程（IS）（有自由参数），以及（vii）一个新的模型，耗散Gramstad-Trulsen （dGT）方程。dGT方程没有自由参数，解决了与dythe和vdythe方程相关的一些困难。我们比较了总体误差的测量和光谱振幅、平均值和峰值的演变。我们发现：(1)NLS和dythe方程不能准确地预测实测的谱幅。（ii） Gordon方程是光学中一个成功的FD模型，但无论选择何种自由参数，都不能准确地模拟水波中的FD。（iii） dNLS、vdythe、dGT和IS（具有优化的自由参数）模型都能合理地预测测量的光谱振幅，但没有一个模型能捕获所有的光谱演变。（iv） vdythe、dGT和IS（自由参数优化）模型对观测到的光谱峰和光谱均值的演化预测效果最好。(v)经过自由参数优化的IS模型在四个实验中的三个实验中具有最小的总体误差。在其他实验中，vdythe方程的总体误差最小。
Frequency downshift (FD) in wave trains on deep water occurs when a measure of the frequency, typically the spectral peak or the spectral mean, decreases as the waves travel down a tank or across the ocean. Many FD models rely on wind or wave breaking. We consider seven models that do not include these effects and compare their predictions with four sets of experiments that also do not include these effects. The models are the (i) nonlinear Schrodinger equation (NLS), (ii) dissipative NLS equation (dNLS), (iii) Dysthe equation, (iv) viscous Dysthe equation (vDysthe), (v) Gordon equation (Gordon) (which has a free parameter), (vi) Islas-Schober equation (IS) (which has a free parameter), and (vii) a new model, the dissipative Gramstad-Trulsen (dGT) equation. The dGT equation has no free parameters and addresses some of the difficulties associated with the Dysthe and vDysthe equations. We compare a measure of overall error and the evolution of the spectral amplitudes, mean, and peak. We find: (i) The NLS and Dysthe equations do not accurately predict the measured spectral amplitudes. (ii) The Gordon equation, which is a successful model of FD in optics, does not accurately model FD in water waves, regardless of the choice of free parameter. (iii) The dNLS, vDysthe, dGT, and IS (with optimized free parameter) models all do a reasonable job predicting the measured spectral amplitudes, but none captures all spectral evolutions. (iv) The vDysthe, dGT, and IS (with optimized free parameter) models do the best at predicting the observed evolution of the spectral peak and the spectral mean. (v) The IS model, optimized over its free parameter, has the smallest overall error for three of the four experiments. The vDysthe equation has the smallest overall error in the other experiment.