Limit of the lyne-type vortices of the pulsatile flow in a curved pipe.

Abstract

The fully developed periodic laminar flows of incompressible Newtonian fluid through a pipe of circular cross section, which is coiled in a circle, have been simulated numerically. The existence of a four-vortex secondary flow system in oscillatory flow was first pointed by Lyne. Even in the pulsating flow, if the amplitude ratio of the volumetric flow rates β is small, the Lyne-type secondary flow patterns appear. The behavior of Lyne-type vortices is investigated for the range 15.07 l De l 176.22, 22.87 l Wo l 50.00, and 0.00 l β l 0.10, and the description of the cause and mechanism of this phenomenon is presented. It is found that the flow patterns are mainly governed by Wo and that the secondary flow in the central core disappears at β g 0.1, unlike in the steady flow.