Modelling the Effects of Fluid-Structure Dynamic Interaction on Aquatic Plants

水生植被是河流和沿海生态系统的重要组成部分。阻力、局部湍流和平衡重构强烈依赖于植被的几何和生物物理性质，从而影响栖息地的健康、运输现象和洪水风险。了解流-植被相互作用在生态系统恢复和基于自然的解决方案(如盐沼、海草和红树林)的性能方面具有重要的国内外战略意义。本项目旨在建立一个计算高效的非线性结构模型，以高度逼真地捕捉多茎水生植物的流体强迫重构。首先，扩展现有单茎模型的原理和应用范围，将多茎植物描述为网络结构(即由集中质量、刚性连杆和旋转弹簧组成的运动链)。分析中将考虑大变形和非线性弹性(即新模型将同时考虑材料和几何非线性)；其次，该项目将把结构模型与最先进的开源流体动力学求解器(即OpenFOAM)耦合，以严格研究几种情况下流固耦合的影响。最后，将积极寻找机会对数值结果进行实验验证。

Aquatic vegetation is an essential component of riverine and coastal ecosystems. Drag forces, local turbulence, and equilibrium reconfigurations strongly depend on the geometric and biophysical properties of the vegetation, which then affect the health of the habitat, transportation phenomena, and flood risk.Understanding flow-vegetation interactions is of great strategic importance nationally and internationally due to their role in ecosystem restoration and the performance of nature-based solutions (e.g., salt marshes, seagrasses, and mangroves).Building on previous exploratory investigations led by the academic supervisors, this project aims to establish a computationally efficient nonlinear structural model to capture with a high degree of fidelity the fluid-forced reconfiguration of multi-stem aquatic plants. First, the principles and range of application of existing single-stem models will be extended by describing multi-stem plants as network-organised structures (i.e., as kinematic chains made of lumped masses, rigid links and rotational springs). Large deformations and nonlinear elasticity will be included in the analyses (i.e., the new model will cater for both material and geometrical nonlinearities).Second, the project will couple the structural model with a state-of-the-art open-source fluid dynamic solver (namely, OpenFOAM) to rigorously investigate the effects of fluid-structure interaction in several scenarios.Finally, opportunities for the experimental validation of the numerical results will be actively sought.