Effects of Aspect Ratio and Mass Distribution on Settling Cylinders
Open Access
- Author:
- Bowie, Brayden
- Area of Honors:
- Mechanical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Margaret Louise Byron, Thesis Supervisor
Daniel Humberto Cortes Correales, Thesis Honors Advisor - Keywords:
- nonspherical
settling
intermediate Reynolds number
mass distribution
cylinder - Abstract:
- Particle-laden flows are widespread in nature, playing an important role in many processes including the global carbon cycle and the transport of pollutants. Naturally occurring aggregates are composed of complex geometries, which results in nonspherical particles with a center of mass (CoM) not located at the same location as the center of buoyancy (CoB). In this study, nonspherical particles were simplified to cylinders in order to investigate settling velocities and trajectories. Cylinders were 3D printed out of two materials: Polyethylene Terephthalate Glycol (PETG) and Acrylonitrile Styrene Acrylate (ASA). Utilizing 3D printing allowed for the CoM to be easily varied by changing the percentage of each material. Cylinder aspect ratios (AR) ranged from 1 to 4. The cylinders, with intermediate Reynolds numbers (Re) on the order of 100, were dropped horizontally into a tank of still (tap) water. The settling velocity and trajectories of the cylinders were recorded, and the orientations of the falling cylinders were qualitatively observed. Results demonstrated that 3D printed non-uniform display experimentally measured settling velocities close to theoretically predicted velocities, regardless of variations in mass distribution. Four different falling behaviors were observed: (1) vertical trajectory/horizontal-periodic orientation (2) vertical trajectory/vertical-periodic orientation (3) constant slanted trajectory and orientation and (4) periodic slanted trajectory and orientation. All cylinders, regardless of falling behavior and mass distribution, experienced the denser (PETG) material pointing downward. As AR increased, periodic oscillation in cylinder orientation increased. At a transitional state, cylinders no longer experienced these periodic oscillations and fell at a steady equilibrium angle. These results validate the use of material extrusion 3D printing for future studies in the settling of CD cylindrical particles and have important implications for a greater understanding of naturally occurring nonspherical particles.