珠江河口底边界层湍流事件研究

Turbulent events research within the bottom boundary layer in the Pearl River Estuary

该文通过座底式支架的ADV,对珠江河口底边界层的湍流进行了一个全潮25 h的观测,并利用该资料对湍流事件进行了研究,探讨了湍流事件特征量在潮内的变化。研究结果表明:(1)河口湍流事件受潮汐过程的影响,各特征量变化带有明显的半日分潮特征,且急流和憩流时刻差异显著。(2)对于动量事件,憩流时刻事件发生的次数多,但持续时间短,贡献率低,而急流时刻次数少,持续时间长,贡献率高;对于泥沙事件,憩流时刻次数少,但持续时间长且强度高,急流时刻次数多,但持续时间短且强度低。(3)湍流事件发生的时间约占总时间的40%,事件的平均持续时间分别为0.07 s(动量事件)和0.05 s(泥沙事件)。

Acoustic Doppler velocimeter （ADV） is installed in the bottom mounted tripod and sampled for 25hours. The turbulent flux events analysis was performed for the entire data sets and the variations of turbulent events were discussed in tidal period. The results show that： （1） For the estuary where the semidiurnal tidal current is dominant, the turbulent event parameters exhibit a strong quarter-diurnal variation, and the different between peak tide and slack tide is significant. （2） The flux events occur more frequently but last for a short time, and the contribution rate to the total flux is low at slack tide, but the features offlux event are contrary at peak tide time. For the sediment events, it is with characteristics of low frequency, long duration and high intensity at slack tide, but of high frequency, short duration and low intensity at peak tide. （3） The occurrence time of events accounts for 40% of total time, and the average duration is 0.07s and 0.05s for the flux events and the sediment events, respectively.