Numerical Simulations of the Physical Process for Hailstone Growth

1. IntroductionTheoretical and experimental studies on the phys-ical processes of hail growth (Schumann, 1938; Lud-lan, 1958; List, 1963) showed that its growth rate andstructural characteristics depend on the heat and masstransfers; its dynamic characteristics determine hail-stone's movement and stay in clouds and damage doneto ground bodies, actually controlling the growth in-side clouds. As we know, the heat transfers affectsdirectly hailstone's wet growth, melting and evapo-ration. In the…

Numerical Simulations of the Physical Process for Hailstone Growth

Theoretical and experimental studies show that during hail growth the heat and mass transfers play a determinant role in growth rates and different structures. However, many numerical model researchers made extrapolation of the key heat transfer coefficient of the thermal balance expression from measurements of evaporating water droplets obtained under small Renolds numbers (Re 200) introduced by Ranz and Marshall, leading to great difference from reality. This paper is devoted to the parameterization of measured heat transfer coefficients under Renolds numbers related to actual hail scales proposed by Zheng, which are then applied, to Hu-He 1D and 3D models for hail growth respectively, indicating that the melting rate of a hailstone is 12%-50% bigger, the evaporation rate is 10%-200% higher and the dry-wet growth rate is 10%-40% larger from the present simulations than from the prototype models.