Turbulence, Sediment Stratification and Altered Resuspension under Waves (TSSAR Waves)

可靠的近岸地区水深变化模型对于研究全球变暖和相对海平面上升对沿海的影响，以及对沿海工程项目的合理评价和实施具有重要意义。此外，增加对沿海资源的利用，如海洋可再生能源发电，需要对波浪和海流下的沉积物运输过程有深入的了解。目前，基于当前对工作过程的理解的水深变化模型通常无法可靠地再现近岸形态变化的基本特征，例如滨沙洲迁移的方向。即使是这类模型中最复杂的例子，也需要对模型自由参数进行看似特别的调整，才能开始给出合理的结果。波浪下湍流、沉积物分层和再悬浮（TSSAR波）项目旨在提供更完整的关于悬浮沉积物瞬时流动分层和悬浮沉积物湍流之间双向反馈影响的知识。对这一过程的初步研究表明，这一过程是一个关键过程，可以为基于过程的模型提供目前缺乏的预测能力。拟议的研究结合了一系列方法来确定沉积物分层在近岸形态发展中的作用。这些包括继续发展研究沉积物-湍流相互作用的数值方法，以便能够表示由一系列沉积物粒度组成的真实沉积物，重点实验室实验将用于确认和校准数值方法中使用的近似值，旨在验证现场条件下数值研究结果的现场测量，最后提出了虚拟冲浪带的开发与应用，该虚拟冲浪带将包含一个基于过程的近岸形态变化模型。通过在虚拟冲浪区打开和关闭沉积物-湍流相互作用的能力，可以直接观察到沉积物分层在水深演化中的重要性，并且通过与实地实验期间收集的观测结果进行比较，预测能力的改进将是显而易见的。由于悬浮液中沉积物粒度分布的组成是TSSAR波的重要组成部分，一种基于激光全息的新型粒度相机将用于实验室和现场测量。普利茅斯大学开发的水下全息成像仪可以收集数字记录的全息图，这些全息图在进行数值重建后，可以提供有关颗粒形状特征和尺寸分布的详细信息。

Reliable models of bathymetric change in the nearshore region are of fundamental importance for studies on the coastal impacts of global warming and relative sea level rise as well as for appropriate evaluation and execution of coastal engineering projects. Furthermore, increased utilization of coastal resources such as that due to marine renewable energy generation necessitates a solid understanding of the processes of sediment transport under waves and currents. Presently, models of bathymetric change which are based on current understanding of the processes at work are typically incapable of reliably recreating even the basic characteristics of nearshore morphology change such as the direction of longshore bar migration. Even the most sophisticated examples of such models require seemingly ad-hoc adjustments of model free parameters to begin to give reasonable results. The Turbulence, Sediment Stratification and Resuspension under Waves (TSSAR Waves) project is designed to provide more complete knowledge about the effects of the two way feedback between instantaneous flow stratification by suspended sediment and the turbulence which suspends that sediment. Preliminary study of this process, which is not accounted for in current concepts of sediment transport, suggests that it is a critical process which may provide process based models the predictive capability they currently lack. The proposed research combines a range of approaches to determine the role that sediment stratification plays in the development of nearshore morphology. These include continued development of the numerical methods for studying sediment-turbulence interactions to permit representation of realistic sediments which are composed of a range of sediment grain sizes, focused laboratory experiments which will be used to confirm and calibrate approximations used in the numerical approach, field measurements designed to validate the results of the numerical studies under field conditions, and finally the development and application of a virtual surf-zone which will contain a process based model of nearshore morphology change. The importance of the role of sediment stratification in bathymetric evolution will be directly observable through the ability to turn the sediment-turbulence interactions on and off in the virtual surf-zone and improvements in predictive capability will be evident by comparison to observations collected during the field experiment. As the makeup of the distribution of sediment grain sizes in suspension is an important component of TSSAR Waves, a new type of particle sizing camera, based on laser holography will be utilized in the laboratory and field measurements. The submersible holographic imager which was developed at the University of Plymouth enables the collection of digitally recorded holograms which, following numerical reconstruction, provide detailed information on particle shape characteristics and size distributions.