Reynolds number effects on turbulent wakes generated by rectangular cylinders with streamwise aspect ratios between 1 to 4

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dc.contributor.authorLiu, Manqi
dc.contributor.examiningcommitteeWang, Bing-Chen(Mechanical Engineering)
dc.contributor.examiningcommitteeEssel, Ebenezer (Mechanical Engineering)
dc.contributor.supervisorTachie, Mark
dc.date.accessioned2023-06-29T17:46:12Z
dc.date.available2023-06-29T17:46:12Z
dc.date.issued2023-06-28
dc.date.submitted2023-06-29T02:39:18Zen_US
dc.degree.disciplineMechanical Engineeringen_US
dc.degree.levelMaster of Science (M.Sc.)
dc.description.abstractThe effects of streamwise aspect ratio and Reynolds number on the separated shear layer and near wake of rectangular cylinders in uniform flow are investigated experimentally using a particle image velocimetry system. Four length-to-height ratios (AR = 1, 2, 3 and 4) are examined at Reynolds numbers (based on freestream velocity and cylinder height) of 3000, 7200, 14700 and 21000. The flow characteristics are examined in terms of the mean flow, Reynolds stresses, probability density function (PDF), joint probability density function (JPDF), turbulent kinetic energy, as well as turbulence production and its transport. The results show that the separated shear layer is either shed directly into the wake region (AR1 and AR2) or reattaches onto the cylinder (AR4), regardless of the Reynolds number. Meanwhile, a transitional regime occurs for AR3 where mean flow reattachment on the cylinder is highly dependent on Reynolds number. The peak magnitudes of the Reynolds stresses, turbulent kinetic energy, turbulence production and its transport are highest for AR1. Aspect ratio and Reynolds number also have significant effects on shear layer transitioning from laminar to turbulence but the transition lengths, when normalized by the corresponding value at Re = 3000, follow a universal power decay law. The wake characteristics, including the recirculation length and wake formation lengths, are independent of Reynolds number for AR1 but decreases with Reynolds number for the longer cylinders, while AR2 shows the largest values. The probability density functions, and joint probability density functions are used to examine the effects of Reynolds number on the fluctuating velocities and momentum transport in the shear layer and near-wake region.
dc.description.noteOctober 2023
dc.identifier.urihttp://hdl.handle.net/1993/37397
dc.language.isoeng
dc.rightsopen accessen_US
dc.subjectParticle Image Velocimetry
dc.subjectturbulent flow
dc.subjectuniform flow
dc.subjectrectangular cylinders
dc.subjectReynolds number effects
dc.subjectaspect ratio effects
dc.subjectflow separation
dc.titleReynolds number effects on turbulent wakes generated by rectangular cylinders with streamwise aspect ratios between 1 to 4
dc.typemaster thesisen_US
local.subject.manitobano
oaire.awardNumberRGPIN-2017-04957
oaire.awardTitleInvestigation of Asymmetric Free and Confined Three-dimensional Turbulent Jets using Time-Resolved Tomographic Particle Image Velocimetry
oaire.awardURIhttps://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=734053
project.funder.identifierhttps://doi.org/10.13039/501100000038
project.funder.nameNatural Sciences and Engineering Research Council of Canada
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