Liquid Residence Time Distribution in a Cavity Driven by Turbulent Channel Flow

Due to the diverse hydraulic phenomena arising from rectangular cavity geometry, the complexity of flow behavior within cavities remains not fully understood in terms of flow residence time. In the present work, the fluid flow field and residence time distribution in cavities of different sizes are experimentally investigated. The effects of the height of the cavity and the liquid flow rate on the mean residence time and the residence time distribution were quantitatively evaluated. Through dimensionless analysis, an empirical relationship equation is derived that successfully relates mean residence time with dimensionless parameters such as the Reynolds number and the cavity’s height-to-length ratio. Finally, based on the flow behavior in the cavity and the liquid flow field obtained by particle image velocimetry, a model of cavity flow is proposed. The model’s F curve equation is derived using material balance, and the model results agree well with the experimental results. This study sheds light on the role of flow residence time in cavity flow, deepening our understanding of fluid mechanics in the cavity and laying a good foundation for the design of pipelines or reactors with such cavity structures.