Local air circulation is influenced by the drag forces exerted by urban vegetation. In this study, tree canopy parameterization in computational fluid dynamics (CFD) with source term modifications is conducted at the tree scale, which builds upon the models previously used in the literature. A simplified three-dimensional model representing tree canopies is resolved and validated against available wind tunnel experiment. The prediction of turbulence kinetic energy (TKE) is shown to be highly sensitive to the model coefficients in the source term of turbulence dissipation rate (TDR). No optimal set of the model coefficients in the TDR source term can be identified. However, ${C_{\epsilon 4}\text{>}\text{C}}_{\text{ε5}}$ is found to better reproduce the turbulent quantities behind the canopy than ${{\text{C}}_{\text{ε4}}\text{=}\text{C}}_{\text{ε5}}$. The reduction of $C_{\epsilon 5}$ value from 1.5 to 0.4 yields a higher TDR source term level by one order of magnitude. The prediction of the mean velocity is primarily controlled by the form drag coefficient, which is heavily correlated to all source terms and their components. Results indicate the feasibility of using a more straightforward modification method in the vegetated microclimate simulations by only adding momentum source terms.

局部空气流通受城市植被施加的阻力的影响。在这项研究中，在树尺度上进行了带有源项修改的计算流体动力学（CFD）中的树冠参数化，该树尺度建立在先前文献中使用的模型的基础上。简化了表示树冠的三维模型，并根据可用的风洞实验进行了验证。在湍流耗散率（TDR）的源项中，湍流动能（TKE）的预测对模型系数非常敏感。无法确定TDR源项中的模型系数的最佳集合。然而，${C_{\epsilon 4}\text{>}\text{C}}_{\text{ε5}}$ 被发现比在顶篷后能更好地再现湍流量 ${{\text{C}}_{\text{ε4}}\text{=}\text{C}}_{\text{ε5}}$。减少$C_{\epsilon 5}$从1.5到0.4的值会产生较高的TDR来源条款水平一个数量级。平均速度的预测主要由形式阻力系数控制，该形式阻力系数与所有源项及其组成部分密切相关。结果表明，通过仅添加动量源项，在植被微气候模拟中使用更直接的修改方法的可行性。