The effect of canopy heterogeneity on mean and turbulent transport processes is studied using a scaled wind-tunnel model of a vineyard canopy with gap spacings of one, two, and three canopy heights. A row-normal freestream velocity component is applied to each canopy configuration and spatial distributions of velocity across a streamwise-vertical plane centred around a single canopy gap are measured using particle imaging velocimetry. Mean flow features including an updraft in the centre of the canopy followed by a descent and recirculation just upstream of the downstream row are observed to decrease in size and magnitude for larger canopy gaps. Turbulence in the canopy sublayer (CSL) is dominated by a growing mixing layer that originates at the top of the upstream row and consumes the underlying weak more isotropic turbulence. The mixing layer’s rate of growth into the CSL decreases as the canopy gap widens, but not enough to offset the increased downstream distance. The vertical extent of the mixing layer into the canopy before being impeded by the downstream row is the main factor that determines horizontal heterogeneity of turbulence in the canopy. An analysis of the Reynolds-averaged turbulence-kinetic-energy budget points to shear production being the main source of turbulence near the canopy top, while turbulent transport is responsible for the growth of the mixing layer down into the CSL.

使用间隙间距为 1、2 和 3 个树冠高度的葡萄园树冠的比例风洞模型研究树冠异质性对平均和湍流传输过程的影响。行法向自由流速度分量应用于每个冠层配置，并使用粒子成像测速仪测量以单个冠层间隙为中心的流向垂直平面上的速度空间分布。观察到平均流量特征，包括冠层中心的上升气流，然后在下游行的上游下降和再循环，对于较大的冠层间隙，其尺寸和幅度都会减小。冠层亚层 (CSL) 中的湍流主要由一个不断增长的混合层主导，该混合层起源于上游行的顶部，并消耗了底层较弱的各向同性湍流。随着冠层间隙的扩大，混合层进入 CSL 的增长率降低，但不足以抵消下游距离的增加。混合层在被下游行阻碍之前进入冠层的垂直范围是决定冠层中湍流水平异质性的主要因素。对雷诺平均湍流动能预算的分析表明，剪切产生是冠层顶部附近湍流的主要来源，而湍流传输是混合层向下生长到 CSL 的原因。混合层在被下游行阻碍之前进入冠层的垂直范围是决定冠层中湍流水平异质性的主要因素。对雷诺平均湍流动能预算的分析表明，剪切产生是冠层顶部附近湍流的主要来源，而湍流传输是混合层向下生长到 CSL 的原因。混合层在被下游行阻碍之前进入冠层的垂直范围是决定冠层中湍流水平异质性的主要因素。对雷诺平均湍流动能预算的分析表明，剪切产生是冠层顶部附近湍流的主要来源，而湍流传输是混合层向下生长到 CSL 的原因。