Modelling Bending Behaviour of Flexible Submerged Vegetation Based on Fluid-Structure Coupling

The bending behaviour of flexible submerged vegetation in water flow has been an important issue in ecological hydraulics; however, the understanding of its laws is still not in-depth enough, and a comprehensive exploration of the governing parameters remains lacking. To address this gap, a three-dimensional numerical model based on fluid-structure coupling was built in this paper and validated by experimental data. Utilizing this model, the bending behaviour of a single vegetation in various scenarios was simulated and analysed. The relationships between the relative bending height (RBH) and critical variables such as flow velocity, vegetation radius, elastic modulus and submergence ratio were found and fitted with different types of equations. Through multiple regression, a comprehensive formula to estimate the RBH of single submerged flexible vegetation was derived based on the simulation results. The formula established in this paper can quickly characterize the bending state of flexible vegetation in water, providing a basis for calculating water flow resistance and contributing to ecological, engineering and environmental studies.