Convection transport between microchannel flow and microcavity vortex under steady flow conditions

This is the authors' abstract. We don't add key points for this paper.

To reveal the fluid transport behaviors between the main flow in microchannels and the laminar vortex in confined microcavities under steady-state conditions, we conducted dye flow visualization experiments and computational fluid dynamics simulations in this study, providing a quantitative analysis of the underlying transport mechanisms. An O-shaped dye flow pattern occupies the majority of the microcavity at a Reynolds number of 46.68. As the Reynolds number increases from 58.36 to 81.70, a hook-shaped dye flow pattern emerges near the entrance of the microcavity, while a U-shaped dye flow pattern develops in the deeper regions of the microcavity. The two convection transport pathways observed in this study represent a novel finding, experimentally indicating that the main flow can directly enter the laminar vortex. The three-dimensional morphological features and transport contributions of the observed flow patterns were further characterized based on streamline distribution and dimensionless transport quantities. The results demonstrate that fluid convection varies non-monotonically with increasing Reynolds number between the main flow and laminar vortex under stable flow conditions. Additionally, the specific pathways of the main flow entering the microcavity are influenced by a combination of several factors, including its initial position in the z- direction, fluid inertia, and velocity gradients in the confined space. These findings provide valuable insights for guiding the design of microcavity devices and enhancing the understanding of natural and physiological phenomena at relevant microscales.