Some Thoughts on Modelling Hail Impact on Surfaces

Hail impact-induced erosion has the potential to significantly affect the operational lifetime of structures exposed to extreme weathering environments such as hail events. Computational materials modelling can be used to better understand the erosion behaviour during a hailstone impact, and here the relevant background work is detailed. In this paper, an implementation of an ice impact model, utilising Smooth Particle Hydrodynamics along with a highly strain-rate-dependent material model, is shown, and its results and limitations discussed. An overview is given on the literature on modelling hail events, including the history of experimental work. The various potential modelling methods which have been developed is then given, along with an evaluation of the suitability of the methods to future work in this area.

Review of Impact Factors of the Velocity of Large Hailstones for Laboratory Hail Impact Testing Consideration

The terminal velocity of hailstones is an essential quantity in hail research. It is an important value for the kinetic energy of hailstones and has to be carefully considered when laboratory hail impact testing is being planned. Many standardized hail impact testing procedures require specific impact velocities. Several empirical models for various hailstone diameter ranges have been developed to calculate the velocity based on the diameter, indicating somewhat inconsistent results. The velocity is influenced by factors such as their density, drag coefficient, shape or air density, and strong winds. This article takes a closer look into each of these factors and how they influence the velocity of hailstones and the damage potential of hailstorms. Implications are made for laboratory testing of hail impact testing procedures and how the geographic location of hailstorms might be a considerable factor when designing a test.