Modified FAE method based on CFD simulation for predicting snowdrift on gable roofs

In cold and snowy regions, roof slopes can affect the snow distribution on the gable roof. The finite area element (FAE) method is modified by considering the effect of the snow transport rate, the developmental law of snow transport and the saturated transport distance on the calculation of drifting snow load in this paper. Saltation and suspension of snow transport are also considered respectively in the process of modification. Then, based on the modified FAE method and computational fluid dynamics (CFD), the influence of roof slopes (10 degrees, 20 degrees, 30 degrees and 40 degrees) on the gable roof snow distribution is studied. Meanwhile, for compare the simulation results of the modified FAE method with different combinations of the snow transport rate, the developmental law of snow transport and the saturated transport distance, the test of wind-blown snow redistribution is completed in the wind tunnel using the substitute particles (silica sand) on the scaled gable roofs. The results show that when the saturated transport distance of snow is 210 m, the modified FAE method can reproduce the snowdrift phenomenon on the gable roof more reasonably if adopting the snow transport rate proposed by Owen (1964) and the developmental law of snow transport suggested by O'Rourke et al. (2005) at the same time. Through CFD simulation, it's discovered that the distribution of flow field around the gable roof and friction velocity on snow surface change noticeably with roof slopes, resulting in the increase of the upwind erosion flux and the leeward deposition flux with the incoming wind speed and the roof slope. In addition, when the incoming wind speed remains unchanged, simulation results using the modified FAE method show that the larger slope of the gable roof, the more likely it is to cause the uneven distribution of snow load on the windward and leeward roofs. Moreover, fresh snow is more likely to cause the uneven distribution of snow load on gable roofs than aged snow through analysis sensitivity of the threshold friction velocity.