In this study, the airflow characteristics around an isolated flat-roof building with different stable snowdrifts were investigated by adopting the Particle-Image-Velocimetry (PIV) wind tunnel experiments and Large-Eddy Simulations. First, the geometric model to be tested was obtained using a 3D printing technique, where the snowdrift pattern on the roof was provided by the results of previous wind tunnel tests conducted by the authors. Second, PIV wind tunnel experiments were carried out to measure flow information on the middle plane of the tested models (with or without snow cover). The specific physical variables (such as mean wind velocity, turbulence kinetic energy (TKE)) was then systematically analysed, which will be an important validation database to verify the LES method. Finally, the effects of the snowdrift on the time-averaged flow field, the turbulence flow field, and the wind load force acting on the buildings were discussed in detail using the LES method. The relevant research results indicate that the existence of snowdrifts changed the geometrical aerodynamic characteristics of the original roof, rendering the shape more streamlined. Thus, it significantly accelerated the passing velocity of the incoming flow over the roof, which results in the decreasing magnitudes of time-averaged Reynold stresses in the flow field above the roof. Additionally, the existence of snowdrifts can effectively restrain the size of the separation bubbles in the separating-reattachment flow field, which leads to vortices of smaller size and higher frequency being formed on the roof. Furthermore, the mean and fluctuations of wind pressure on the windward side of snowdrifts roof have larger magnitude than a roof without snow, which may increase the risk of damage to local enclosure structures near the windward side of the roof.

在这项研究中，通过采用粒子图像测速（PIV）风洞实验和大涡模拟，研究了具有不同稳定雪堆的隔离式屋顶建筑物周围的气流特性。首先，使用3D打印技术获得要测试的几何模型，其中作者的先前风洞测试结果提供了屋顶上的积雪图案。其次，进行了PIV风洞实验，以测量测试模型（带或不带积雪）的中间平面上的流量信息。然后系统地分析了特定的物理变量（例如平均风速，湍流动能（TKE）），这将是验证LES方法的重要验证数据库。最后，使用LES方法详细讨论了雪堆对时间平均流场，湍流流场和作用在建筑物上的风荷载力的影响。相关研究结果表明，雪堆的存在改变了原始屋顶的几何空气动力学特性，使形状更加流线型。因此，它显着地加速了进入的流动通过屋顶的速度，从而导致屋顶上方的流场中时间平均雷诺应力的幅度减小。另外，雪堆的存在可以有效地限制分离-重新附着流场中分离气泡的尺寸，这导致在屋顶上形成较小尺寸和较高频率的涡流。此外，