Enhancement of Heat Transfer in a Microchannel via Passive and Active Control of a Jet Issued from the Circular Cylinder

The heat transfer enhancement of a jet issued from the circular cylinder placed in three-dimensional microchannel at low Reynolds numbers were studied systematically by using numerical simulation. effects on thermal efficiency evaluated varying injection ratios (I) and angles (θ). physical mechanism was revealed through analyses vorticity dynamic temperature field. results showed that proportional to ratio Re = 100 200. However, 300, did not increase monotonically with ratio, local maximum value efficiency, slightly less than highest appeared I 1.5. This result inducing vortex generated become unstable. Furthermore, change angle had better effect performance compared ratio. separation point flow over vortices near field adjusted angle. At appropriate range angle, wake transitioned quasi-steady unsteady far instability can disturb boundary layer wall so as improve performance.