A numerical study of mechanisms of accretion for rotating snow sleeves evolving on conductor rods

Abstract

AbstractIt is the purpose of this paper to construct a mathematical/computational model for the accretion of snow on rotating snow sleeves attached to conductor rods, and to consider some of the limitations in the use of the assumption of perfect cylindrical‐sleeve growth, as currently employed to provide estimates of snow‐loading intensity.For purposes of illustration, three rotating snow accretion regimes are considered, in which the direction of the airflow is always taken as perpendicular to the axis of the conductor rod. Firstly, a horizontal conductor rod is free to rotate and is initially bare. Rotation of the system (conductor rod and accreted snow) is initiated by snow torque, due to eccentric snow loading on the windward side of the conductor, and is driven by aerodynamic torque generated by the windflow past the evolving, rotating, asymmetrical sleeve growth. Secondly, a vertical conductor rod is free to rotate and the bare rod is given an initial small angular velocity; the rotation of the accreting system is then driven by aerodynamic torque alone. Thirdly, a horizontal rod is fixed and is initially covered by an annulus of snow, supported by a thin layer of (unfrozen) water existing between the conductor and the snow sleeve. In this case, the rotation of the snow sleeve is due to the combined snow and aerodynamic torques and is now retarded by the viscous torque due to the rotating thin film of water.Asymptotic solutions obtained for small accretion time supplement numerical results derived from the computational models. Numerical results on these rotating non‐periodic snow accretion regimes are presented as a function of the wind speed, snow precipitation rate and diameter of the conductor rod.