Investigation of temperature-induced flow stratification and spiral flow in T-shaped microchannel

Abstract

In this study, the heat and fluid flows were investigated when fluids at varying temperatures are mixed in a T-shaped microchannel. A temperature gradient was formed using two Peltier modules in the junction of a T-shaped microchannel, and the velocity fields were measured using microparticle image velocimetry (µ-PIV). Measurements were obtained at five planes in the direction of the depth by changing the focal position of the objective lens. Under the operation of the Peltier modules, the flow velocity on the heated side was increased and the velocity on the cooled side was decreased in the upper area in the vertical direction. Furthermore, in the lower area, the flow velocity on the cooled side was increased and the velocity on the heated side was decreased. The velocity difference between the two inlets depends on the applied power of the Peltier modules. We also investigated the mixing behavior downstream of the channel, and a strong spiral flow was clearly observed. The spiral flow should enlarge the contact interface area, and it should be useful for application to a micromixer. We first observed the fluid stratification induced by the temperature in the microchannel. This phenomenon is useful for application in microfluidic devices as a contactless micromixer.