Canopy flow is the flow over roughness elements such as plants, fibers, and buildings, and is important to many environmental and engineering issues such as the transport of pollutants/nutritions in the forest and aquatic swamps, the transport of pollutants in cities, wind farms, etc. We have studied the canopy flow over aquatic plants of different flexibilities by large-eddy simulation of fluid-structure interaction.

Traditionally, the canopy is modeled as uniform porous media with a constant, a priori drag coefficient (which is usually not the case in reality), and the elements in the canopy are not resolved, whereas we resolved every element and modeled the canopy as an array of stems. Our model has three advantages. First, introducing the unphysical constant, a priori drag coefficient is not necessary. Second, the stem-scale flow structures inside the canopy can be resolved. Third, the flow-induced traveling waving motion of the canopy, which is significant to the transport of momentum and turbulent kinetic energy across the canopy top, can be resolved. Please refer to more of our researches on flows with wavy boundaries.

A movie for the flow structure and canopy deformation is shown below, where the wavy motion of the canopy can be observed.

Selected Publications:

• He, S., Liu, H. & Shen, L. (2022), “Simulation-based study of turbulent aquatic canopy flows with flexible stems,” Journal of Fluid Mechanics, Vol. 947, A33.