Abstract：
Oyster populations within the Chesapeake Bay have been drastically reduced over the last century mainly due to unregulated human activities and diseases. Regulations and restoration efforts have focused on restoring oyster populations while also considering their ability to provide ecosystem services, such as coastal protection and water quality improvement, among others. To promote oyster growth and the settlement of new populations, a recent technique adopted along the east coast of the US is the use of oyster castles (OCs). OCs have proven effective in recruiting and retaining oysters and in promoting both vertical growth and horizontal expansion of oyster habitats. OCs are widely used in coastal protection as greener alternative to common engineering solutions. We quantified hydrodynamic differences that occur around these OCs during their early stage (i.e. castles without oysters), and with fully developed oysters covering the surface of the castles through a series of laboratory experiments. The experiments were conducted in a recirculating Odell-Kovasznay type channel at the Ecohydraulics and Ecomorphodynamics Laboratory (EEL) at the University of Illinois. OCs (both with and without oysters) were 3D printed at 1:7 scale to fit the canal, and Particle Image Velocimetry (PIV) was used for 2D flow characterization. Data showed noticeable differences in flow acceleration atop the castles when covered with oysters, as well as an increase in the generation and distribution of turbulent kinetic energy atop and around the oyster-covered castles. Magnitudes and spatial distribution of Reynolds stresses were also affected by the presence of oysters in both submerged and near-emergent conditions. Challenges associated with the estimation of the drag coefficient for both gray and oyster-covered OCs highlighted the need for more data besides the centerline 2D PIV output. Further research involving the whole three-dimensional structure of the flow, in both unidirectional and oscillatory conditions, will allow us to provide relevant guidelines on the design and use of oyster-populated breakwaters as a viable nature-based solution for coastal protection within low-energy environments.
摘要：
在过去的一个世纪中，切萨皮克湾内的牡蛎数量已经大幅减少，主要是由于不受管制的人类活动和疾病。法规和恢复工作的重点是恢复牡蛎种群，同时考虑其提供生态系统服务的能力，例如海岸保护和水质改善，在其他人中。为了促进牡蛎的生长和新种群的定居，最近在美国东海岸采用的技术是使用牡蛎城堡（OC）。事实证明，OC可以有效地招募和保留牡蛎，并促进牡蛎栖息地的垂直生长和水平扩展。OCs广泛用于沿海保护，作为常见工程解决方案的绿色替代方案。我们量化了在早期阶段（即没有牡蛎的城堡）围绕这些OC发生的流体动力学差异，并通过一系列实验室实验，充分开发的牡蛎覆盖了城堡的表面。实验是在伊利诺伊大学生态水力学和生态形态动力学实验室（EEL）的循环Odell-Kovasznay型通道中进行的。OCs（有和没有牡蛎）以1：7的比例进行3D打印以适应运河，和粒子图像测速（PIV）用于二维流动表征。数据显示，当覆盖有牡蛎时，城堡顶部的流动加速度存在明显差异，以及在牡蛎覆盖的城堡顶部和周围的湍流动能的产生和分布增加。在淹没和接近紧急情况下，牡蛎的存在也会影响雷诺应力的大小和空间分布。与灰色和牡蛎覆盖的OC的阻力系数估计相关的挑战强调了除了中心线2DPIV输出之外还需要更多数据。进一步研究涉及流动的整个三维结构，在单向和振荡条件下，将使我们能够提供有关牡蛎密集的防波堤的设计和使用的相关指南，作为在低能耗环境中进行沿海保护的可行的基于自然的解决方案。
