Type of Document Master's Thesis Author Ortega Lopez, Miguel Dario Author's Email Address miguelo@vt.edu URN etd-05052009-121041 Title Exploring and Envisioning Periodic Laminar Flow Around a Cylinder Degree Master of Science Department Engineering Science and Mechanics Advisory Committee

Advisor Name Title Kriz, Ronald D. Committee Chair Dancey, Clinton L. Committee Co-Chair Ragab, Saad A. Committee Member Keywords

- qualitative analysis
- second invariant of the velocity gradient
Date of Defense 2009-04-24 Availability unrestricted AbstractIt is well known that for small Reynolds numbers, flow around a cylinder is laminar and stable.For larger Reynolds numbers, although the flow regime remains laminar, the formation of

complex periodic structures appear downstream. The cyclic nature of this periodic flow is well

characterized by the vortex shedding frequency and Strouhal number. However, complexities of

these periodic structures downstream continue to be a topic of research. Periodic laminar 2D

incompressible viscous flow around a cylinder is simulated using OpenFoam, an open source

computational fluid dynamics program. To better understand these complex structures

downstream, a customized computer graphical tool, VerFlow-V.01, was created to analyze and

study OpenFoam simulation results. This study includes an investigation of calculating the

details of drag and lift coefficients for the cylinder using mathematical models that integrate

properties in subdomains, an approach not previously explored to the knowledge of the author.

Numerical integration is accomplished using a finite difference approach for solving surface and

contour integrals in subdomains of interest. Special attention is given to pressure and to the

second invariant of the velocity gradient, as they have a clear mathematical relationship, which is

consistent with results previously published. A customized visual data analysis tool, called

VerFlow-V.01, allowed investigators to compare simulation data variables in a variety of useful

ways, revealing details not previously understood. Main subroutines and a user’s manual are

included as appendices to encourage reproducibility and future development of the numerical,

analytical and graphical models developed here. Together these models resulted in a new

understanding of periodic laminar flow around a cylinder. A unique approach was developed to

qualitatively understand the origins of drag and lift coefficients associated with properties

mapped as images in subdomains of interest downstream. These results explain the development

of convergent, eddy, and stream zones embedded in flow fields downstream.

Files

Filename Size Approximate Download Time (Hours:Minutes:Seconds)

28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access 01e_Exploring_and_Envisioning_Periodic_Laminar_Flow.pdf4.49 Mb 00:20:48 00:10:41 00:09:21 00:04:40 00:00:23 A1.1_reverse_FS.wmv696.93 Kb 00:03:13 00:01:39 00:01:27 00:00:43 00:00:03 A4.1_Forces_FS.mov428.31 Kb 00:01:58 00:01:01 00:00:53 00:00:26 00:00:02 A4.2_Rect_FS.mov3.59 Mb 00:16:36 00:08:32 00:07:28 00:03:44 00:00:19 A4.3_EntireDomain_FS.mov4.43 Mb 00:20:29 00:10:32 00:09:13 00:04:36 00:00:23 A4.4_stagQDragFull_FS.mov9.29 Mb 00:43:00 00:22:07 00:19:21 00:09:40 00:00:49 A4.5_stagQLiftFull_FS.mov8.01 Mb 00:37:05 00:19:04 00:16:41 00:08:20 00:00:42 A4.6_StagVortVelVectors_FS.mov7.92 Mb 00:36:41 00:18:52 00:16:30 00:08:15 00:00:42

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