Simulation-based study on turbulent canopy flows and "Monami" phenomenon

To understand the dynamics of flow and canopy motions and the energy transfer in turbulent canopy flows, we performed a high-fidelity simulation based study using large-eddy simulation. Our simulation employs an immersed boundary method together with a beam model to capture the dynamics of individual filaments in canopy stem arrays. Our simulation resolves the turbulence-induced coherent waving of the stems, which is known as Monami. A broad range of stem flexibilities are considered in the simulation. Two characteristic scales are identified through spectral analyses. One is the Monami scale which is related to the progressive waving of the canopy, and the other one is the wake scale which is related to the wake behind each filament. A spectral TKE budget analysis indicates that the waving term plays an important role in the inter-scale and wall-normal energy transport processes. Moreover, the spectral shortcut process proposed by previous studies are found to be caused by the waving term.