Flow regime refers to the pattern of flow behavior in a fluid system, influenced by factors such as velocity, viscosity, and channel characteristics. In geology, flow regimes are studied in the context of sediment transport, river dynamics, and volcanic eruptions to understand the movement of fluids and the resulting landforms.
Source Middleton, G. V., & Southard, J. B. (1984). Mechanics of Sediment Movement. SEPM Society for Sedimentary Geology.