CLASSIFICATION OF PULSATING FLOW PATTERNS IN CURVED PIPES

The fully developed periodic laminar flow of incompressible Newtonian fluids through a pipe of circular cross section, which is coiled in a circle, was simulated numerically. The flow patterns are characterized by three parameters. the Womersley number Wo, the Dean number De, and the amplitude ratio beta. The effect of these parameters on the flow was studied in the range 2.19 less than or equal to Wo less than or eq ual to 50.00, 15.07 less than or equal to De less than or equal to 265 .49 and 0.50 less than or equal to beta less than or equal to 2.00, wi th the curvature ratio delta fixed to be 0.05. The way the secondary f low evolved with increasing Womersley number and Dean number is explai ned. The secondary flow patterns are classified into three main groups : the viscosity-dominated type, the inertia-dominated type, and the co nvection-dominated type. It was found that when the amplitude ratio of the volumetric flow rate is equal to 1.0, four to six vortices of the secondary flow appear at high Dean numbers, and the Lyne-type flow pa tterns disappear at beta greater than or equal to 0.50.