A Numerical Investigation of Turbulent Interchange Mixing of Axial Coolant Flow in Rod Bundle Geometries

Abstract

This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus. some thesis and dissertation copies are in typwriter face, while others may be from any type of cornputer printer.The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct prÏnt, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment c m adversely affect reproduction.In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages. these will be noted. Also, if unauthonzed copyright material had to be rernoved, a note will indicate the deletion.Oversize materials (e-g., maps, drawings, charts) are reproduoed by sedioning the original, beginning at the upper left-hand corner and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is induded in reduced form at the back of the book.Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. As a result, radial diffusion processes (such as pressure drop) were predicted accuratelbut azimuthal diffusion processes (such as turbulent interchange rnixing) were underpredicted. An isotropic eddy viscosity turbulence model, therefore, is not recommended for analysis of turbulent interchange mixing. Acknowledgement sWithout question, this Masters thesis benefited k o m the assistance of a number of people.For technical advice and support, 1 thank

Validation of DES-SST Based Turbulence Model for a Fully Developed Turbulent Channel Flow Problem

“…The long term research aims at numerically identifying the presence of largescale coherent structures in tightly packed rod bundle geometries and their effects on the turbulence structure and heat transfer characteristics [42][43][44]. Numerical identification of these structures is possible using inherently unsteady turbulence modeling approaches like DES or LES that resolve the large scale turbulence fluctuations.…”