During a snowfall, the surfaces of the snow beds on roofs change dynamically with time and wind conditions. The generation of body-fitted computational fluid dynamics grids for simulating dynamic snow surfaces using the moving-grid method remains challenging. Therefore, a numerical method was developed to simulate the fluid–solid transition based on the volume of the fluid model and solidification and melting models. The snowfall process was divided into stable steps, and a stable state calculation method was adopted to calculate the air and snow phases. The dynamic snow boundary was simulated at each stage by converting the fluid or solid characteristics of the domain in which the grids resided. Based on the results of the (−1) stage, the fluid domain grids buried by the snow were filled with liquid and frozen into the solid domain. Instead, the fluid in the frozen grids, where snow was about to be eroded, was evacuated and converted into fluid-domain grids. Thus, a complex and changeable snow boundary could be adapted without re-meshing. A modified wall friction velocity equation was derived to correct the wall friction velocity at the snow boundary owing to the serrated boundary of the solidified grids, thereby improving calculation accuracy. The numerical simulation results were verified via field observations of snow distribution on the stepped flat and gable roof models. The snow variation on a full-scale, three-span, suspended cable roof under snow-fall conditions was predicted using the proposed method.

中文翻译：

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基于VOF和SAM模型的流固转变数值模拟及大跨屋面积雪分布预测

降雪期间，屋顶雪床的表面会随着时间和风力条件而动态变化。使用移动网格方法生成贴身计算流体动力学网格来模拟动态雪面仍然具有挑战性。因此，开发了一种基于流体模型和凝固熔化模型的体积模拟流固转变的数值方法。将降雪过程分为稳定步骤，采用稳态计算方法计算风相和雪相。通过转换网格所在域的流体或固体特征，在每个阶段模拟动态雪边界。根据（-1）阶段的结果，被雪掩埋的流体域网格充满液体并冻结到固体域中。相反，冻结网格中即将被雪侵蚀的流体被抽空并转换为流体域网格。因此，可以在不重新划分网格的情况下适应复杂且多变的雪边界。推导了修正的壁面摩擦速度方程，修正了由于凝固网格边界呈锯齿状而导致的雪边界处的壁面摩擦速度，从而提高了计算精度。通过对阶梯式平屋顶和人字形屋顶模型上积雪分布的现场观测，验证了数值模拟结果。使用所提出的方法预测了降雪条件下全尺寸三跨悬索屋顶的积雪变化。