Enhanced heat and mass transfer in a microchannel using separated circular bluff body and L-shaped flexible micro-beam

The asymmetric flexible vortex generator (FVG), consisting of an L-shaped flexible micro-beam attached to a circular bluff body, is an effective strategy for facilitating the vortex shedding, thereby enhancing the heat transfer and fluid mixing of microchannel flow at low Reynolds numbers. To further improve the heat and mass transfer performance, this paper proposes a modified design in which the circular bluff body and the L-shaped flexible micro-beam are separated and investigates the effects of this separation on the Nusselt number, outlet mixing efficiency, and pressure drop of the fluid flow inside a microchannel at three different circular diameter-based Reynolds numbers Red = 25, 50, and 100. The results demonstrate that the separated vortex generator facilitates the transition from laminar flow to vortex flow more effectively than the no-separation design. For the quantitative effects on the heat and mass transfer performance, the separation shows limited effect at Red = 25. However, at Red = 50 and 100, the separation between the circular bluff body and the L-shaped flexible micro-beam obviously enhances the Nusselt number and outlet mixing efficiency compared to those of the non-separated vortex generator, though with increased pressure loss. The maximum increases in the Nusselt number and outlet mixing efficiency reach 28.47% and 426.31%. This work provides a promising approach to design the asymmetric FVG through structural separation, enhancing heat transfer and fluid mixing of microchannel flow.