Date of Award

5-16-2024

Publication Type

Thesis

Degree Name

M.A.Sc.

Department

Mechanical, Automotive, and Materials Engineering

Keywords

incidence angle;jet;PIV;recirculation;slot;Wall-mounted

Supervisor

Monsif Shinneeb

Supervisor

Ram Balachandar

Abstract

An experimental study was conducted to understand the effect of the angle of incidence on the wake flow characteristics of an emergent slotted circular cylinder immersed in a shallow flow. Four incidence angles θ = 0°, 30°, 60°, and 90° were considered, and the results were compared with the plain cylinder case, which served as a reference case. In this study, the ratio of the slot thickness to cylinder diameter (s/d) is 0.10. The bulk velocity of the channel flow is 0.29 m/s, resulting in a Reynolds number, based on the cylinder’s diameter, of 14,500. PIV measurements were made along the vertical x-y mid-plane (z/d = 0.0) and on three horizontal x-z planes at elevations y/H = 0.1, 0.5, and 0.9. Two thousand image pairs were acquired at each location at a frequency of 3.63 Hz. The objectives were achieved by investigating the mean velocity field and turbulence characteristics in the wake flow. The results revealed that wake flow is characterized by the formation of a counter-clockwise (CCW) recirculation zone on the vertical plane and a pair(s) of counter-rotating recirculation zones on the horizontal plane. Moreover, the velocity profile of the jet at θ = 0° is characterized by a mild peak located in the lower half of the water depth and its magnitude decreases gradually upward to form an S-shape resulting from the interaction of the recirculation zone with the jet from the slot. For zero incidence angle (θ = 0°), the jet-like flow emanating from the slot into the wake exhibits an oscillatory behaviour, flipping between two distinct states. From the Reynolds normal stress, there is a reduction in the influence of the jet on the streamwise velocity fluctuations, which is manifested in a systematic expansion and increase in the magnitude of the stress throughout the velocity field for θ ≥ 30. Furthermore, the Reynolds shear stress reveals that the momentum of the jet reduces as the angle of incidence changes from 0 to 30 degrees. When transitioning to incidence angles of 60 and 90 degrees, the Reynolds shear stress peak is higher on the shear layers and closer to the bluff body.

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