Turbulent Buoyant Plumes from Time-Varying Sources

Turbulent buoyant plumes occur in a wide range of natural and industrial processes, including wildfires, volcanic eruptions, and methane leaks. As a plume rises, it expands due to the entrainment of ambient fluid at its edges. Previous research has explored the turbulent dynamics and corresponding entrainment of both steady plumes and starting plumes with steady source conditions via analytical, experimental, and numerical approaches. However, the behavior of turbulent buoyant plumes arising from time-varying sources has received comparatively less attention. In this study, we use direct numerical simulations to investigate the dynamics and entrainment processes of plumes driven by time-varying sources. We connect these processes to the structure of the overall plume and the turbulent features at the plume edge.