ICONE23-1241 VISUALIZATION OF CHAOTIC MIXING INDUCED BY OSCILLATORY FLOW IN A CURVED TUBE

Abstract

The objective of this study is to visualize the chaotic mixing patterns induced by oscillatory flow in a curved tube. The velocity field during oscillatory flow in a curved tube with inner diameter of 10 mm and tube length of 314 mm was numerically simulated using the commercial software Fluent. The working fluid was water and the flow was assumed to be 3D, laminar, unsteady, and incompressible. To clarify the effect of the curvature, the ratio of the tube radius to the curvature radius a/b was varied from 0.0125 to 0.075, and oscillatory flow frequency f was varied from 0.5 to 2.0 Hz. To visualize the fluid mixing patterns, trajectories were also calculated for the minute particles that follow convective movement. To examine the chaotic features of flow, the largest Lyapunov exponent was then evaluated. The visualized tracer patterns revealed the characteristic fluid mixing patterns with repeated stretching and folding in the radial and longitudinal cross-sections, and the length of a stretched tracer line increased with increasing a/b and with decreasing f. The average value of the largest Lyapunov exponent was positive under all flow conditions and was changed in response to the tracer line length. These results indicate that the flow mixing pattern induced by oscillatory flow in a curved tube is chaotic.