Numerical simulations of development of snowdrifts on long-span spherical roofs

摘要

This study aims to provide a multiphase approach that could better consider the snow drifting development on a building roof and then apply it to the investigation of the snowdrift development on a long-span spherical roof. Firstly, the CFD prediction accuracy for the flow field and the snowdrift on a two-level step building is examined by comparing simulated results with that of a field measurement. The windward snowdrift caused by building's blocking effect and trajectories of snow particles under the action of aerodynamic force and gravity are both well reproduced by incorporating an additional source term and a slip term into the transport equations. Secondly, the prediction accuracy of the snowdrift formed on a spherical roof is confirmed through the comparison with a wind tunnel test. The snow slipping effect at the edge of the roof is also well reproduced by considering the angle of repose of the snow. Based the validated approach, the snowdrift characteristics on a long-span spherical roof are investigated under different inflow velocity conditions. Three kinds of distribution patterns, i.e., the full-span balanced distribution, half-span unbalanced distribution and transitional distribution between them, are observed. Furthermore, the predicted results correspond well with the resultant design codes developed by ISO 4355. Finally, the size effect of the building roof on snowdrifts is explored by simulating the snowdrift on the spherical roofs with different spans. It is found that the spherical roof would have to bear a larger snow load with the increasing roof span, namely, the long-span spherical roof has more risks due to the adverse snow load.