2026-09-24T01:03:12Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/50345 2023-07-11 col_2142_5131 col_2142_14787 com_2142_5130 com_2142_9630 com_2142_234

Georgiadis, John G. Georgiadis, John G. Jacobi, Anthony M. Brewster, M. Quinn Litchfield, J. Bruce Georgiou, Marios 2014-09-16T17:11:53Z 2014-09-16T17:11:53Z 2016-09-22T20:59:25Z 2014-08 2014-09-16 2014-08 The study of natural convection in enclosures has attracted the attention of numerous researchers over the past decades due to its applications in many practical engineering problems. Some examples include air conditioning and ventilation systems, electronic cooling devices, heat exchangers and thermal storage. In the present work an experimental investigation of natural convection developed in an air filled cube of side H=0.35m is conducted using Particle Image Velocimetry (PIV) to measure the velocity field within the cavity and visualize the dominant flow structures. The low turbulence Rayleigh number regime 5.08E7<Ra<3.40E8 is examined for the first time and experimental results including streamlines, the two velocity components in the vertical and horizontal direction, Reynolds stresses, swirling strength and vorticity are reported. In addition, Proper Orthogonal Decomposition (POD) was employed to analyze the flow and identify its major components. The estimated error from PIV measurements is within 1-2%, thus the high accuracy of the results can form experimental benchmark data and can be used to validate future CFD codes. Flow visualization enabled the study of the evolution of the boundary layers along the isothermal and adiabatic walls. Furthermore, two secondary re-criculations in the upper left and lower right corner of the cavity where measurements were conducted were also observed and reported. The two regions are anti-symmetric with the one in the upper left corner being initially stronger. Finally, heat transfer measurements on the hot wall were conducted and Nusslet number for the corresponding Rayleigh number was estimated. A correlation between the two numbers was obtained and compared against other correlations in the literature. A deviation from the classical power law theory was observed and it is attributed to radiation and non-Boussinesq effects. A concurrent computer simulations effort was also conducted and the results are presented for comparison with experimental data. Item withdrawn by Laura Spradlin (lspradl2@illinois.edu) on 2014-06-27T21:26:15Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Georgiou_Marios.pdf: 78296058 bytes, checksum: 49134d7dac09c7ce5d554825c43dd4e3 (MD5) Made available in DSpace on 2014-09-16T17:11:53Z (GMT). No. of bitstreams: 2 Marios_Georgiou.pdf: 78288506 bytes, checksum: 2b3d39f8ce9281c36025f23b9bd0a5a4 (MD5) license.txt: 4065 bytes, checksum: 29d460b738c5428b68cd3e9b04af68a1 (MD5) Embargo set by: Seth Robbins for item 50456 Lift date: 2016-09-16T17:13:01Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system Limited Restriction Lifted for Item 50456 on 2016-09-22T20:59:25Z. http://hdl.handle.net/2142/50345 en Copyright 2014 Marios Georgiou Natural convection enclosures Particle Image Velocimetry (PIV) Proper Orthogonal Decomposition (POD) Particle image velocimetry for natural convection in a cube at high Rayleigh numbers text Mechanical Sci & Engineering 1917 Mechanical Engineering 0133 University of Illinois at Urbana-Champaign Dissertation Ph.D. PHD:Mechanical Enginerng -UIUC 10KS0133PHD