A predictive approach to elucidate the interaction between wave-induced flows and vegetation

人为变化对气候的一个主要影响是海平面的加速上升。这种上升预计会改变近地表波的传播速度和携带的动能，挑战天然海岸植被防止侵蚀和减轻洪水风险的有效性。在这个项目中，我们的目标是朝着量化盐沼植被的动能耗散和波调制的预测方法迈出一步。我们通过将植物尺度的特性整合到通过植被的自由表面流的空间分解单元中来实现这一点。在这个项目的框架内要实现两个主要目标：第一个目标是为羊草开发一个能够在植物尺度上描述流动-植被相互作用的数值盐沼模型。该盐沼模型的植物建模基于Kirchhoff-Love理论，得到了相应的茎和叶尺度的机械/组织学实验，以及基于时间分辨层析PIV和单株植物力测量的高分辨率流场和压力场的规范数据集的支持。一方面，该模型可以作为分析植被的力学和几何或建筑特性对波浪衰减影响的一种经济有效且可转移的工具。目前，对这种依赖性的观察结果还远远不够一致，植物弯曲刚度、浮力和茎/叶密度所起的相对作用仍存在争议。另一方面，盐沼模型为更大规模的物理描述提供了一个跳板。利用这些数值工具和相应的实验结果，将通过三维增材制造和在波通道中实验采样的方式创建单个植物和完整植物群落的替代系统。以这种方式产生的羊草替代植物的盐沼部分代表了该项目的第二个主要目标。有了这个替代系统，就有可能不需要对真实的植物群落进行昂贵的采样，这在国家公园中测试波浪通道中盐沼植被之间的相互作用行为尤其重要。此外，盐沼植被几乎可以在不同条件和重复条件下进行任意数量的系统实验。

A major impact of anthropogenic changes to our climate is the accelerated rise in sea level. This rise is expected to alter the propagation velocity and kinetic energy carried by near-surface waves, challenging the effectiveness of natural coastal vegetation in preventing erosion and mitigating flood risk. In this project, we aim to take a step towards a predictive approach to quantifying kinetic energy dissipation and wave modulation by salt marsh vegetation. We do this by integrating plant-scale properties into a spatially resolved unit section of free surface flow through and over vegetation.Two main goals are to be achieved within the framework of this project: The first objective is to develop a numerical salt marsh model for Elymus that is able to describe the flow-vegetation interaction at the plant scale. This salt marsh model, whose plant modelling is based on the Kirchhoff-Love theory, is supported by corresponding mechanical/histological experiments at the culm and leaf scale, as well as by canonical data sets of high-resolution flow and pressure fields based on time-resolved tomographic PIV and force measurements on individual plants. On the one hand, this model can serve as a cost-effective and transferable tool for analysing the influence of mechanical and geometric or architectural properties of vegetation on wave attenuation. Currently, observations on this dependence are far from consistent and the relative roles played by plant bending stiffness, buoyancy and culm/leaf density are still controversial. On the other hand, the salt marsh model provides a springboard for a physical description on even larger scales. With these numerical tools and the corresponding experimental results, replacement systems for individual plants and complete plant communities will be created by means of three-dimensional additive manufacturing and experimentally sampled in the wave channel. The salt marsh section of Elymus replacement plants generated in this way represents the second main objective of this project. With this replacement system it is possible to do without costly sampling of real plant communities, which is especially important in national parks to test the interaction behaviour between salt marsh vegetation in the wave channel. Furthermore, almost any number of systematic experiments under different conditions and repetitions can be realised in the salt marsh vegetation.