Wind Tunnel Test of Snow Redistribution on Roofs
A series of wind tunnel tests were carried out to predict snow distribution on roofs. A typical stepped roof and two gable roofs were investigated. Model snow depth distributions on the roofs were measured at various time intervals. The effects of velocity and wind direction were studied, and mass transport rates on the roofs were examined as well. The results show that, the saltation of particles decreases the turbulence intensity nearby the surface, and the effective aerodynamic roughness-lengths of the field are proportional to the 2nd power of the friction velocities. At the wind direction of 0°, the snow depth distribution on the stepped roof is well consistent with the field observation. Snow depth distributions on the stepped roof are quite unbalanced under oblique winds, especially at wind direction of 135°, the snow depth coefficients range from 0 to 1.7. The leeward side of the gable roofs may accumulate more snow at wind direction of 0°. The maximum coefficients are 1.7 and 1.2 for slope 10° and 20° respectively. The mean mass flux rates on the roofs are proportional to velocities, implying that the mass transport rate increases with the 3rd power of the friction velocity.