Numerical simulation and wind tunnel test for redistribution of snow on a flat roof

Abstract

A real snowstorm often lasts for hours to several days. Simulating snow drifting on a roof through traditional transient method of computational fluid dynamics would be time consuming. Thus, a quasi-steady method is proposed in this paper to simulate redistribution of snow on roofs. The process of snow drifting is divided into several phases according to the characteristics of meteorological data. The erosion/deposition of snow in each phase is regarded as a steady state. In the numerical simulation, the angle of repose of snow is taken into account. The boundaries of snowpack are updated based on the calculated results of change rate of snow depth in the previous phase. The proposed numerical method was applied to predict snow redistribution on a flat roof. A scaled test was conducted in a wind tunnel to validate the accuracy of the numerical simulation, in which a kind of high-density particle, silica sand, was used to model snow particles. The snow redistributions obtained from the numerical simulation agree well with those from the test results. As the wind tunnel test, the numerical simulation also predicted deposition on a small windward area of the flat roof. Then the transport rate of snow or silica sand on roof surface was investigated. The influence of the threshold velocity of snow and silica sand on prototype duration was also studied. Finally the snow redistribution on a flat roof during a real snowstorm was simulated in this study to show the practicability of the proposed method.