Numerical Simulation of Lightning Channel Expansion during the Return Stroke Stage

This work presents a physico-mathematical model of the processes occurring in an ionized lightning channel formed as a result of a return stroke. The results of numerical simulations are provided, demonstrating that the combined consideration of Joule heating and multigroup radiative transfer leads to the formation of a complex structure in the distributions of the ionized channel parameters. This structure is caused by the presence of two temperature gradients (ahead of the shock front and at the boundary of the conductive region), which arise due to radiative transfer. The obtained results can be used in the development of three-dimensional self-consistent numerical models of lightning channel dynamics.