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Title:Studies in Unsteady Penetrative Thermal Convection
Author(s):Kumar, Ranganathan
Department / Program:Theoretical and Applied Mechanics
Discipline:Theoretical and Applied Mechanics
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Applied Mechanics
Abstract:This study concentrates on the dynamics and structure of turbulence in the interfacial region and the upper part of a mixed layer which is capped by a linearly stratified, non-turbulent region. Measurements of the local, instantaneous values of the temperature, the vertical velocity and horizontal velocity have been made using a thermocouple and a two-component dual beam laser Doppler velocimeter.
Vertical profiles of all relevant one-point moment including joint temperature-velocity moments up to fourth order have been obtained. Mean temperature measurements have been made for various kinematic heat flux settings to understand the thermal structure in the entrainment zone. Conditional averaging techniques and probability density functions have been employed to infer the properties of fluid elements in the mixed layer. A length scale in the interfacial layer, based on the temperature gradient in the stable region has been proposed.
Power spectra for velocity and temperature have been analyzed to check the possible existence of inertial subrange and estimate the noise level. With the aid of flow visualization, a phenomenological model of penetrative convection for low entrainment rate has been developed.
Issue Date:1983
Description:165 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.
Other Identifier(s):(UMI)AAI8324590
Date Available in IDEALS:2014-12-16
Date Deposited:1983

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