Effect of Corner Radius of a T-Junction Mini-square Channel on Fluid Flow and Heat Transfer in the Developing Region: A Three Dimensional Numerical Simulation

In recent years, there is a trend of miniaturization of devices like heat exchangers, microfluidic devices, MEMS and electronic chip devices. The study of fluid flow in these devices is of great significance nowadays. Due to small dimensions, the entrance design is a matter of concern and importance. In this work, the effect of variation of corner radius, on thermo- hydrodynamic characteristics of a three dimensional model of T-junction square mini-channel duct of 2 mm sides is studied under constant heat flux applied (H2 type) on the horizontal part. The length of horizontal section is 300 mm. The T junction is placed at the middle of 60 mm long vertical section. The numerical simulation was done in general purpose CFD package FLUENT. The simulation is performed for two Reynolds number, one in laminar flow range (Re 1000) and the other in turbulent flow range (Re 3200). It is observed that incorporation of fillets at T-junction changed the nature of the fluid flow and heat transfer locally. Variations in velocity and Nusselt number have been observed in both the laminar and turbulent flow regime. Within developing region local velocity is found to be increasing with increase in corner radii towards downstream of the channel in laminar and turbulent flow. Whereas the local Nusselt numbers are less as compared to base model for all heating conditions and corner radii, resulting in local wall temperature rise. Hence, such incorporation of corner radii may accelerate the uniform flow velocity growth. Vortices are observed to be diminishing near the junction with increase in corner radii.