Two-dimensional numerical simulation of a decaying laser spark in air with radiation loss

Results are presented on two-dimensional numerical simulation of a decaying laser spark after the air breakdown. Radiation loss is modeled in a finite volume framework for a finite wavelength range of the emitted rays. The redistribution of assumed absorbed energy among different parts, namely the blast wave energy, the radiative heat energy and the left-over energy is quantified. About 5% of the absorbed energy is found to be trapped around the breakdown region after the blast wave moves away. A prediction is made about the actual available energy for ignition of a combustible mixture. A distinct rollup motion around the breakdown region is demonstrated from the simulation, which is in accordance with other numerical and experimental observations. Finally, the evolution of the blast wave radius with time is validated against in-house experimental data.