Simulation of the destruction of a woodland massif by the shock wave generated by the impact of a large cosmic body

The interaction of shock waves with woodland massifs with consideration given to vegetation destruction is examined. The results of numerical simulations of the propagation of a perturbation through a vegetation massif based on solving the Euler equations for two-dimensional and axisymmetric cases are presented. This approach was used by the present author in simulating the propagation of wave fronts through woodland massifs without regard for forest stand destruction. The effect of vegetation is reproduced by introducing bulk forces in the volume occupied by forest. An initial perturbation of explosion-in-flight type was specified in the form of an increased-pressure region located at various heights from the ground surface. Simple threshold models are used to examine the effect of the dynamic pressure on vegetation destruction. A refined model was developed to investigate the change in the configuration of woodland massifs with consideration given to vegetation fall and the effect of this process on the rate of perturbation dissipation. The system of equations was solved by the Godunov method implemented using parallel programming. Numerical experiments were conducted with the use of two types of models of forest stand destruction, with various threshold values of the destruction factor, various initial perturbation intensities, and various heights above the vegetation massif. The effects arising during the interaction of a high-intensity perturbation with a woodland massif were identified. An analysis of the results showed that the destruction of vegetation occurs during its interaction with the fronts of the incident and reflected shock wave and with the jet core of the perturbation. In some cases, the model taking into account the accumulation of fallen vegetation predicts situations where destruction will occur only in the upper part of the forest stand, without touching the canopy. This effect can explain the existence of such regions in the area of the Tunguska event. It was also demonstrated that estimates of the sizes of the destruction zones obtained with the use of the models taking into account the influence of vegetation on the perturbation and destructibility differ substantially from those obtained within the framework of the models without regard for vegetation resistance. The highest range of perturbation dissipation was predicted by the models simulating the formation of obstructions.