Thermally-driven microfluidic swirler for flow manipulation

Abstract

In this work, an original thermally-driven micro-fluidic swirler for flow manipulation applications is proposed. The swirling mechanisms are thermally activated only. Since the device does not require any moving parts, it is robust and needs extremely low maintenance. The swirling effect is triggered by activating a temperature gradient transversely to the stream-wise direction of the flow. The swirling mechanism corresponds to a combined effect of advection and natural convection inside a squared cross-section straight micro-channel. We here offer a complete characterization of the micro-fluidic system both from an experimental and numerical point of view. A first numerical design and optimization of the device was realized in respect to the swirling effect for parameters such as the Reynolds number and hydraulic diameter of the channel. Subsequently, the study explored the impact of the flow swirling on the heat transfer mechanisms along the channel. Results are proposed in terms of the Nusselt number for a wide range of channel dimensions. On these basis, a physical microfluidic swirler prototype was developed and was experimentally characterized. The experiments where performed via micro particle image velocimetry ($\mu$ – PIV) and velocity fields results were compared to numerical experiments with excellent agreement.