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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal align=center style='text-align:center;line-height:150%'><span style='font-size:14.0pt;line-height:150%'>Ph.D. Defense<o:p></o:p></span></p><p class=MsoNormal align=center style='text-align:center;line-height:150%'><b>NUMERICAL INVESTIGATION <o:p></o:p></b></p><p class=MsoNormal align=center style='text-align:center;line-height:150%'><b>OF VAPOR BUBBLE INTERACTION WITH A SUPERHEATED WALL<o:p></o:p></b></p><p class=MsoNormal align=center style='text-align:center;line-height:150%'><span style='font-size:14.0pt;line-height:150%'>Mohammad Wasy Akhtar<o:p></o:p></span></p><p class=MsoNormal align=center style='text-align:center;line-height:150%'><span style='font-size:14.0pt;line-height:150%'>Department of Mechanical Engineering<o:p></o:p></span></p><p class=MsoNormal align=center style='text-align:center;line-height:150%'><span style='font-size:14.0pt;line-height:150%'>July 15<sup>th</sup>, 2011 at 9:00 am<o:p></o:p></span></p><p class=MsoNormal align=center style='text-align:center;line-height:150%'><span style='font-size:14.0pt;line-height:150%'>Heat Transfer and Phase Change Laboratory (N263-D)<o:p></o:p></span></p><p class=MsoNormal>Committee:<o:p></o:p></p><p class=MsoNormal>Dr. Stanley J. Kleis, Associate Professor, Chair of the Committee<o:p></o:p></p><p class=MsoNormal>Dr. D. Keith Hollingsworth, Associate Professor, Mechanical Engineering<o:p></o:p></p><p class=MsoNormal style='text-align:justify'>Dr. K. H. Wang, Professor, Civil Engineering<o:p></o:p></p><p class=MsoNormal style='text-align:justify'>Dr. Larry C. Witte, Professor, Mechanical Engineering<o:p></o:p></p><p class=MsoNormal style='text-align:justify'>Dr. Ralph W. Metcalfe, Professor, Mechanical & BioMedical Engineering and Mathematics<o:p></o:p></p><p class=MsoNormal style='text-align:justify'><o:p> </o:p></p><p class=MsoNormal align=center style='text-align:center;line-height:200%'><b><span style='font-size:14.0pt;line-height:200%'>Abstract<o:p></o:p></span></b></p><p class=MsoNormal style='text-align:justify;line-height:150%'> Vapor bubbles, once formed at nucleation sites or released from injection points, may rise under buoyancy effects and slide against adjacent surfaces. In this problem, known as the “sliding bubble problem,” a thin liquid microlayer can form between the bubble and the superheated wall, which can contribute to significant heat transfer enhancement. In order to better understand the sliding bubble problem in terms of microlayer dynamics, large scale dynamics, and their relationship to<span style='font-size:11.5pt;line-height:150%'> heat transfer enhancement</span>, a complete solution of the problem is needed.<o:p></o:p></p><p class=MsoNormal style='text-align:justify;line-height:150%'> This work presents a full three-dimensional numerical simulation of vapor bubble interaction with an inclined superheated wall on an adaptive octree (tree) based grid structure. A robust phase change model was developed to include both liquid and vapor heat fluxes into the interface with heat flux dependent interface temperatures. The validated phase change model was then used to study the dynamics of a growing vapor bubble approaching an inclined heated plate including the bubble approach, wall interaction leading to the development of the microlayer and the initial sliding regimes. Evolution of the heat transfer measures including wall, wake and microlayer regions were quantified for a single vapor bubble interaction with a superheated wall.<o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p></div></body></html>