Numerical Investigation of Swirl flow in Enhancement of Mixing in Narrow Channel

The present work systematically investigates the effect of swirl on the mixing efficiency in narrow channel. Two fluid streams (A&B) with different concentration is considered at the inlet. Rankine-Vortex is used to generate the swirl which results in tangential velocity of flowing field and it can be obtained by solving N-S equation analytically. This leads to disturb the flowing fluid in transverse direction which imitate the mixing. Efficiency of mixing is evaluated from the concentration of the flowing fluid at various cross-section of the channel by solving the species transport equation numerically using finite difference approach. Swirl enhances the chaotic behaviour between the fluid layer results in mixing effectively in short length scale and also it signifies the mixing is advection dominant than diffusion. Results shows that swirl intensity decays fast for lower Reynolds number (Re<1) while Peclet number (Pe) remains constant. As a consequent of swirl decay efficiency of mixing is low and also it signifies that the mixing at Re<1 is highly dominated by molecular diffusion over advection. On increasing the Re>5, significant effect of swirl is observed because of advection component as a result the efficiency of mixing is increased in a shorter length scale.