Numerical simulation of converging nonlinear wavefronts

The propagation of a two-dimensional weakly nonlinear wavefront into a poly tropic gas in a uniform state and at rest has been studied. Successive posi tions of the wavefront and the distribution of amplitude on it are obtained by solving a system of conservation forms of the equations of weakly nonli near ray theory (WNLRT) using a TVB scheme based on the Lax-Friedrichs flux . The predictions of the WNLRT are found to be qualitatively quite differen t from the predictions of the linear theory. The linear wavefronts leading to the formation of caustics are replaced by nonlinear wavefronts with kink s. By varying the initial shape of the wavefront and the amplitude distribu tion on it, the formation and separation of kinks on the wavefront has been studied.