Sunflower detonation
  In this fluid dynamic video we present simulations of converging two-dimensional detonation in a radially expanding supersonic flow of ideal reactive gas. The detonation is found to be unstable and leads to formation of characteristic cellular patterns. Without any obstacles in the flow, the detonation keeps expanding radially. To retain the wave within a bounded region, we place a number of rigid obstacles in the flow so that the detonation shock stands some distance toward the center from the obstacles. This leads to generation of reflected shock waves from the obstacles which help the detonation wave to remain at a finite distance from the source. The cellular structure of detonation creates beautiful patterns of shock waves and contact discontinuities within and after the reaction zone. The patterns often resemble a sunflower, hence the name of "sunflower detonation". 
A. Kasimov and S. Korneev
physics.flu-dyn