An experimental investigation of wind-induced snow drifting on low-rise flat roofs: A systematic analysis with or without snowfall

Wind-induced snow transport plays a key role in uneven snow drift on rooftops, yet the mechanisms driving this transport remain poorly understood. To investigate the mass transport of snow drifting on rooftops, this study systematically conducted a series of wind tunnel experiments using blowing snow on low-rise flat roofs. High-density silica particles were employed, and various test parameters, including snowfall, wind speed, roof span, and blowing duration, were varied. The results showed that the snow-depth shape on the central axis of a roof can be summarized and simplified into four typical patterns according to different test conditions. The average transport rate on a flat roof decreases exponentially with the duration of blowing snow. A greater wind speed will significantly increase the transport rate on the roof. The saturated mass transport rate can be described by a polynomial of the wind speed and particle threshold wind speed under no-snowfall conditions and can be expressed as the product of snowfall intensity and saturated length for snowfall conditions. When drifting snow is not saturated, the initial transport rate on a roof can be expressed as the product of the saturated transport rate and the power function of a roof span, and the power index value is 0.65 for a no-snowfall condition and 0.75 for a snowfall condition. For saturated length, since snowfall leads to an increase in particle mass flux in the saltation layer and a decrease in particle threshold wind speed, the saturated length with snowfall will be smaller than that without snowfall and will decrease with an increase in snowfall intensity. Finally, the snow distribution pattern and blowing snow transport model derived in this study can provide valuable insights for snow load design in practical engineering applications.