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Modal Analysis of Two-Dimensional Wakes With Different Cross-Sections.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Modal Analysis of Two-Dimensional Wakes With Different Cross-Sections./
Author:	Luo, Chenyao.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2023,
Description:	54 p.
Notes:	Source: Masters Abstracts International, Volume: 85-07.
Contained By:	Masters Abstracts International85-07.
Subject:	Mechanical engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30695569
ISBN:	9798381303018

Modal Analysis of Two-Dimensional Wakes With Different Cross-Sections.
Luo, Chenyao.

Modal Analysis of Two-Dimensional Wakes With Different Cross-Sections. - Ann Arbor : ProQuest Dissertations & Theses, 2023 - 54 p.

Source: Masters Abstracts International, Volume: 85-07.

Thesis (M.S.)--University of California, San Diego, 2023.

This item must not be sold to any third party vendors.

Two-dimensional flow over a cylinder is simulated using Ansys Fluent and analyzed using spectral proper orthogonal decomposition (SPOD). Wakes past bluff bodies are common in nature and the understanding of these wakes is crucial to mechanical and environmental engineering. Two-dimensional wakes serve as a good model for the dominant large-scale dynamics of these types of wakes. The vortex shedding Strouhal numbers (St) and associated eigenmodes are extracted. We consider both the effect of the Reynolds number (Re) and the shape of the object by conducting a series of simulations. The effect of the Reynolds number is investigated by simulating circular cylinder wakes at Reynolds numbers at 60, 100, and 150. The influence of varying the shape of the bluff body is examined by conducting simulations at Re = 150 for circular and square cylinders as well as elliptical cylinders with aspect ratios of 0.25, 0.5, and 4. As revealed by SPOD dominant frequencies, the VS Strouhal numbers vary as Reynolds number or body shape changes in a way that is consistent and in quantitative agreement with results from the literature. The spatial modes at St represent wave-like packets of perturbation traveling downstream, corresponding to the vortex-shedding motions. The modes associated with harmonics of the base frequency (St, 2St, 3St, ...) alternate between symmetric and antisymmetric shapes for all cases examined. As the aspect ratio changes from 0.25 to 4, the wakes evolve from bluff body wakes towards slender body wakes, featuring Karman vortices with higher spacing. Particularly, in the case with AR = 0.25, a secondary vortex street emerges in the far wake, characterized by a much larger physical scale and lower frequency as compared to the primary Karman wake.

ISBN: 9798381303018Subjects--Topical Terms:

557493
Mechanical engineering.
Subjects--Index Terms:

Orthogonal decomposition

Modal Analysis of Two-Dimensional Wakes With Different Cross-Sections.
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245 1 0 $a Modal Analysis of Two-Dimensional Wakes With Different Cross-Sections.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2023
300 $a 54 p.
500 $a Source: Masters Abstracts International, Volume: 85-07.
500 $a Advisor: Sarkar, Sutanu.
502 $a Thesis (M.S.)--University of California, San Diego, 2023.
506 $a This item must not be sold to any third party vendors.
520 $a Two-dimensional flow over a cylinder is simulated using Ansys Fluent and analyzed using spectral proper orthogonal decomposition (SPOD). Wakes past bluff bodies are common in nature and the understanding of these wakes is crucial to mechanical and environmental engineering. Two-dimensional wakes serve as a good model for the dominant large-scale dynamics of these types of wakes. The vortex shedding Strouhal numbers (St) and associated eigenmodes are extracted. We consider both the effect of the Reynolds number (Re) and the shape of the object by conducting a series of simulations. The effect of the Reynolds number is investigated by simulating circular cylinder wakes at Reynolds numbers at 60, 100, and 150. The influence of varying the shape of the bluff body is examined by conducting simulations at Re = 150 for circular and square cylinders as well as elliptical cylinders with aspect ratios of 0.25, 0.5, and 4. As revealed by SPOD dominant frequencies, the VS Strouhal numbers vary as Reynolds number or body shape changes in a way that is consistent and in quantitative agreement with results from the literature. The spatial modes at St represent wave-like packets of perturbation traveling downstream, corresponding to the vortex-shedding motions. The modes associated with harmonics of the base frequency (St, 2St, 3St, ...) alternate between symmetric and antisymmetric shapes for all cases examined. As the aspect ratio changes from 0.25 to 4, the wakes evolve from bluff body wakes towards slender body wakes, featuring Karman vortices with higher spacing. Particularly, in the case with AR = 0.25, a secondary vortex street emerges in the far wake, characterized by a much larger physical scale and lower frequency as compared to the primary Karman wake.
590 $a School code: 0033.
650 4 $a Mechanical engineering. $3 557493
650 4 $a Fluid mechanics. $3 555551
653 $a Orthogonal decomposition
653 $a Strouhal numbers
653 $a Secondary vortex
653 $a Primary Karman wake
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690 $a 0204
710 2 $a University of California, San Diego. $b Mechanical and Aerospace Engineering. $3 1241242
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793 $a English
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