基于数据的波驱动湍流表征：采用时间分辨的预报误差增长方法
Data-Driven Characterisation of Wave-Forced Turbulence Using Time-Resolved Forecast-Error Growth
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中文总结 AI 辅助
本研究采用KNN-GMAE预报误差增长协议分析不同波强迫频率下的湍流数据，发现λFEG随频率非单调变化，且时间结构存在显著差异。
中文摘要 AI 辅助
周期性表面波强迫可通过相干频谱响应、同步性、间歇性及短期可预报性变化来重组湍流流动，因此其动力学效应未必随强迫频率单调变化。我们采用通用的KNN-GMAE预报误差增长协议，重新分析了恒定流量下四种工况（0、0.5、0.67、1 Hz）的实验室声学多普勒测速仪记录。距离加权的k近邻预测器会生成多个时效的样本外预报，ln(GMAE)与物理预报时间的早期准线性区域的斜率被记为有限时效预报误差增长率λFEG。对于全部120秒的记录，0、0.5、0.67、1 Hz对应的λFEG分别为5.68、0.85、3.39、4.11 s⁻¹。该排序0 Hz>1 Hz>0.67 Hz>0.5 Hz在全部7组邻近参数配置中均保持一致，说明该对比结果并非单一KNN设置的人为产物。采用10秒步长的40秒滑动窗口分析揭示了显著的时间结构：无波工况的λFEG始终偏高，0.5 Hz工况始终偏低；而1 Hz记录对单一指数增长机制的局部支撑较弱，9个窗口中仅3个满足采用的早期拟合准则RFEG≥0.90，相比之下0、0.5、0.67 Hz工况分别为8/9、7/9、7/9。
英文摘要
Periodic surface-wave forcing can reorganise turbulent flows through coherent spectral response, synchronization, intermittency, and changes in short-term predictability, so its dynamical effect need not vary monotonically with forcing frequency. We reanalyse laboratory acoustic Doppler velocimetry records obtained at constant discharge under four conditions (0, 0.5, 0.67, and 1~Hz) using one common KNN--GMAE forecast-error-growth protocol. A distance-weighted $k$-nearest-neighbour predictor generates out-of-sample forecasts over multiple horizons, and the slope of the early quasi-linear region of $\ln(\mathrm{GMAE})$ versus physical forecast time is reported as a finite-horizon forecast-error-growth rate, $\lFEG$. For the full 120-s records, $\lFEG$ is 5.68, 0.85, 3.39, and 4.11~s$^{-1}$ for 0, 0.5, 0.67, and 1~Hz, respectively. The ordering 0~Hz $>$ 1~Hz $>$ 0.67~Hz $>$ 0.5~Hz is preserved in all seven nearby parameter configurations, indicating that the comparative result is not an artefact of a single KNN setting. A 40-s sliding-window analysis with a 10-s step reveals substantial temporal structure. The no-wave condition remains predominantly high and the 0.5-Hz condition predominantly low, whereas the 1-Hz record has weaker local support for a single exponential-growth regime: only 3 of 9 windows satisfy the adopted early-fit criterion $\RFEG\geq0.90$, compared with 8/9, 7/9, and 7/9 for 0, 0.5, and 0.67~Hz.
