Modelling the Break-Up and Re-Entry Propagation of Meteorites Through a Continuum Approach

The study of the fragmentation of meteorites entering the Earth's atmosphere allow to predict the consequences such events can have on the ground. Existing models for meteoroid fragmentation follow either a pancake approach, where the cloud of fragments resulting from the meteorite explosion expands together in the shape of a disk, or a discrete fragmentation approach, where successive fragmentation events split the bolide into several pieces. In this work, a comprehensive approach in which the fragments resulting from the breakup of a meteorite are modelled using a continuum distribution it is proposed. A modified version of the NASA Standard Breakup Model is used to generate the fragments distribution in terms of their area-to-mass ratio and ejection velocity. This distribution is then combined with the nominal entry state of the meteorite to generate the initial conditions for the entire ensemble of fragments resulting from the breakup. The fragments distribution is then directly propagated using the continuity equation combined with the non-linear entry dynamics, considering both deceleration and ablation. The result is the evolution of the fragments cloud in time, which is then reconstructed at each time step using a Gaussian mixture model. This model moves away from the simplified pancake method and has the flexibility to include large fragmentation events for a better physical representation of the entry of meteorites, given the fragments distribution as an initial condition only. This means that improved meteorites fragmentation models can be easily integrated into this framework for better propagation of the trajectory of the fragments. The propagation of the fragments density and its reconstruction is first compared against Monte Carlo simulations, and then against real observations.