乱流火災の時空構造の複雑さと同期

抄録

The emergence of spatiotemporal chaos produced by spatially extended nonlinear system and chaos synchronization have promoted the sharp growth of much interest in nonlinear physics and related branches of mathematical science. We have numerically studied the spatiotemporal dynamics of flow velocity field in a buoyancy-induced turbulent fire and the synchronization of two coupled turbulent fires from viewpoints of statistical complexity, complex networks, and dynamical systems theory. Two classes of dynamics: (1) low-dimensional deterministic chaos in the near field dominated by the unstable motion of toroidal vortices and (2) high-dimensional chaos in the far field forming a well-developed turbulent plume, dominate the dynamic behavior of a buoyancy-induced turbulent fire. A scale-free structure related to fractality appears in weighted networks between vortices, while its lifetime follows a clear power law, indicating intermittent appearances, disappearances, and reappearances of the scale-free nature. A significant decrease in the distance between the two fire sources gives rise to a synchronized state in the near field. The synchronized state vanishes in the far field, regardless of the distance between the two fire sources.