Three-dimensional particle paths in a lid-driven cavity flow: experiments and analysis
Date Issued
2006
Date
2006
Author(s)
Tsorng, Shuen-Jong
DOI
en-US
Abstract
Experiments and analysis are performed to character three-dimensional particle paths in a lid-driven cavity. Two types of particles with various diameters and experimental methods are utilized in this thesis. Illuminated micro-particles and artificial long exposure techniques visualize two-dimensional flow field. Stereo image methods measure three-dimensional macro-particle positions and Kalman filter efficiently attenuates measurement errors. To complement of experiments, analysis of velocity fields from three-dimensional Navier-Stokes equations in velocity-vorticity formulation solved by finite difference method extract details of flow structures and these computations stand for motions of fluid-particles. Stereo tracking experiments delineate macro-particle shuttling to and fro from side wall to centre plane in spiral way in cavity flow. Mutual comparisons of trajectories and velocities for fluid- (passive tracers), micro- and macro-particles are carried out in Lagrangian and Eulerian viewpoints to highlight similarities and discrepancies among them. There are two interesting phenomena: 1) macro-particle paths are only confined in primary eddy region even if trajectories and velocities of macro-particle matches computational fluid-particle results, whereas fluid- and micro-particles migrate to primary and corner vortices; 2) preferential paths of macro-particle approach to boundary walls while Re increasing. We afterward come up with some possible mechanisms to explain observations such as density mismatch, steric effect, inertia effect and particle rotation. After further examinations, density mismatch is excluded. The steric effect due to particle size gives an evident limitation for invasion of corner eddies through streamline corridors. Inertia effects contain the Reynolds number dependence of macro-particle trajectories and significant deviation of macro-particle rotation rate relative to fluid-particle.
Subjects
三維穴室流場
立體影像技術量測
顆粒追蹤
卡門濾波
顆粒運動
cavity flow
stereo particle tracking
Kalman filter
particle motion
Type
thesis
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