Modeling Variable Viscosity Forced and Free Convection in Porous Media

Hooman, Kamel (2009). Modeling Variable Viscosity Forced and Free Convection in Porous Media PhD Thesis, School of Engineering, The University of Queensland.

       
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Author Hooman, Kamel
Thesis Title Modeling Variable Viscosity Forced and Free Convection in Porous Media
School, Centre or Institute School of Engineering
Institution The University of Queensland
Publication date 2009-02
Thesis type PhD Thesis
Supervisor Professor Halim Gurgenci
Professor Ibrahim Dincer
Total pages 219
Total colour pages 4
Total black and white pages 215
Subjects 290000 Engineering and Technology
Abstract/Summary This thesis addresses modeling transport phenomena in porous media with special attention being paid to convective characteristics of variable viscosity fluids in a homogeneous and isotropic medium. Two different categories of flows, with totally different driving forces, are considered being forced and free convection (both side and bottom heating, for a square enclosure, are studied). To account for property variation, the density is modeled by an Oberbeck–Boussinesq approximation while the viscosity is modeled by an exponential function. The limitations of the previous work, addressing the issue, are discussed in detail and improvements, in terms of thermo-hydraulic performance of the system are suggested. Dealing with the global aspects of the problem, the two major methods being the reference temperature and the property ratio approach are implemented. For natural convection problems, the former method is used; while for forced convection the latter is undertaken. New correlations, which are proved to be more accurate, are proposed for both forced and free convection problems. Besides, closed form solutions are reported for some cases of constant and variable viscosity. Convection visualization is also studied in detail where the concept of Energy Flux Vectors is put forward along with the application of heatlines and energy streamlines. It was mathematically shown that in two-dimensional space heatlines and energy streamlines, which were invented independently, are the same as each other. Moreover, the newly developed concept, energy flux vectors serve as a new tool for convection visualization with the main advantage that this new technique, unlike heatlines and energy streamlines, does not require further (and sometimes complicated) numerical analysis in addition to solving momentum and thermal energy equations. This, in its turn, reduces the time and computer resources required to see the flow of energy. Finally, in Chapter 7, the summary of the work along with the conclusions are presented. Finally, recommendations for future studies are put forward.
Keyword porous media
variable property
free convection
forced convection
numerical
analytical
Additional Notes pages 53-55 should be printed in color so is page 76 of the thesis (not the document) while page 169 is landscape.

 
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Created: Mon, 03 Aug 2009, 09:59:22 EST by Mr Kamel Hooman on behalf of Library - Information Access Service