Momentum and mass exchanges between the atmosphere and forests situated on complex terrain continue to draw significant research attention primarily because of their significance to a plethora of applications. In this paper, we investigated flows behavior on the leeward side of a two‐dimensional forested ridge under neutrally stratified conditions using large‐eddy simulations (LESs). The goal is to understand how variations in leaf area index (LAI), vertical canopy foliage distributions, and forest edge positions affect mean/turbulent flow statistics, momentum fluxes, and onset of recirculation patterns. Although pressure perturbations are dominated by the hill shape, it is demonstrated here that changes in canopy foliage distribution modulate intensities and patterns of the leeward adverse pressure gradients. Such changes in the adverse pressure gradients alter the mean velocity streamlines including the patterns and magnitudes of the leeward downward mean vertical velocity and the velocity variances and momentum flux in the wake region. While a downwind recirculation zone develops in all cases, the details regarding the incipient location and recirculation zone size vary including positions of the separation and reattachment points. Furthermore, changes in the strength and depth of the zone occur due to canopy‐induced changes in adverse pressure gradients, advection, and canopy drag. Because the recirculation zone impacts the local mean advective terms in momentum and scalar exchanges, the simulations here indicate that canopy morphology‐induced changes in the leeward flows have significant implications to both measurements and models of biosphere‐atmosphere exchange over complex terrain.

中文翻译：

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冠层形态对二维孤立岭上流动的影响

大气与位于复杂地形上的森林之间的动量和质量交换继续吸引大量的研究关注，这主要是因为它们对大量应用具有重要意义。在本文中，我们使用大涡模拟（LESs）研究了中性分层条件下二维森林山脊背风侧的水流行为。目的是了解叶面积指数（LAI），垂直冠层树叶分布和森林边缘位置的变化如何影响平均/湍流流量统计，动量通量和再循环模式的开始。尽管压力扰动主要由丘陵形状决定，但此处证明了冠层叶片分布的变化会调节背风不利压力梯度的强度和模式。逆向压力梯度的这种变化会改变平均速度流线，其中包括背风向下平均垂直速度的模式和大小以及尾流区域的速度变化和动量通量。尽管在所有情况下都会形成顺风回风区，但有关初始位置和回风区大小的详细信息会有所不同，包括分离点和重新连接点的位置。此外，该区域的强度和深度也会发生变化，这是由于冠层引起的不利压力梯度，对流和冠层阻力的变化所致。由于回流区会影响动量和标量交换的局部平均对流项，