Turbulent flow across a clearing-forest transition: a large eddy simulation study

Forest fragmentation significantly impacts scalar concentration and momentum fluxes, introducing heterogeneity influencing mass, energy, and meteorological flows. This study focuses on instabilities from clearing-to-forest wind flow, emphasizing the crucial role of advective flows. Using large eddy simulation (LES) with tailored momentum drag, we capture turbulent profiles downstream of the forest. Findings highlight increased skewness near the forest border, indicating wind field variability. Maximum vertical momentum fluxes occur at the canopy top, with positive values at z = 0.5 signifying downward fluxes. Sweeps dominate within the canopy, driving momentum flux transport from wind to forest. Profiles are well-resolved, but high turbulence near the border introduces instabilities, increasing LES uncertainty. Addressing this requires refining clearing fetch and inflow conditions for accurate simulations. Core conclusions involve successful replication of turbulent statistics in clearings, transitions, and canopy turbulence. Intense turbulent structures in forests and occasional overestimations near the surface are observed, with the forest’s edge identified as a significant impact zone. Organized turbulent structures, especially sweeps and ejections, contribute to momentum transport within forests. The positive feedback loop between clearing fetch and inflow conditions, amplifying turbulence at the forest edge, suggests a need for optimization. Acknowledging sub-grid modeling limitations, surface-near instabilities, and turbulent structure representation, future research involves improved sub-grid models, detailed surface-near instability analysis, exploration of organized turbulent structures, and optimization of clearing dimensions and inflow conditions. Addressing these aspects can improve wind flow simulations and enhance understanding of turbulence–canopy interactions.