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Inlet swirl decay and mixing in a laminar micropipe flow with wall slip

In this work, the laminar decaying inlet swirl flow in a straight micro-pipe with wall slip is solved analytically and the solution verified numerically. Based on a fully developed parabolic axial velocity profiles, the swirl velocity equation is solved by the separation of variable technique. The solution is expressed as a function of the flow Reynolds number, the axial distance within the micro-pipe from the inlet, the wall slip and the inlet swirl velocity profile. The effects of the parameters on the swirl velocity distribution and the swirl decay are analyzed along the flow. Addition of a swirling velocity to the flow of a fluid in a pipe is of great importance in enhancement transport characteristics. The current results offer analytical equations to estimate the swirl velocity distribution with slip at the walls for the design of swirl flow devices. Furthermore, to quantify mixing, the change in the average distance traveled by fluid particles from inlet in a swirl flow is compared with the average distance traveled by the fluid particles in case of no swirl. A clear enhancement of the average distance traveled is obtained. In our opinion the present work is useful to researchers looking for enhancement of transport characteristics in micro-pipes.