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Laminar natural convection within long vertical uniformly heated parallel-plate channels and circular tubesVorayos, Nat 27 June 2000 (has links)
The problem of simple mathematical models of laminar natural convective
flow within a long vertical parallel-plate channels and circular tubes kept at
uniformly heated walls is revisited to seek a clear physical understanding of heat
transfer mechanisms. A series solution method to analyze the fully developed flow
and an integral solution method to analyze the developing flow are used. Chapters
3, 4, and 5 of this dissertation constitute a series of three-paper manuscripts for
submission to archival journals.
The channels and circular tubes considered here are assumed to be
sufficiently long to yield a fully developed flow thermally as well as
hydrodynamically before the exit is encountered. In such fully developed flow
situation, the fluid mass flow rate naturally induced into the channel due to
buoyancy is found to be a function of the wall heating condition. The predicted
average Nusselt number as a function of GrPrD/L not only agrees with the existing
literature but also is found to be in a functional form comparable to that proposed
by Elenbaas (1942 a and b). Our results show that, in spite of being driven by
buoyancy (rather than by a pump or a blower), the flow and heat transfer
characteristics in the fully developed regime are essentially the same as those of
fully developed laminar forced convection in which the flow is externally driven.
This observation is confirmed to be valid also in the study (Chapter 5) of
laminar natural convection in the developing (entrance) region within a long
vertical parallel-plate channel and circular tube. The mass flow rate, which has to
remain invariant with axial location even in the entry region, is determined by the
flow in the fully developed region. This is the same mechanism involved in forced
convection in which the fluid outside the developing boundary layers (i.e. the core
flow) is forced to accelerate in the entrance region. The entrance length of channel
natural convection is also discovered to be about the same as that in forced
convection. / Graduation date: 2001
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Natural convection cooling of vertical plates in an enclosure : a numerical simulationDestremau, Axel 07 November 1991 (has links)
Graduation date: 1992
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Natural and mixed convection in a horizontal cylindrical annulus with and without fins on inner cylinderBegum, Latifa. January 2007 (has links)
Determination of the heat transfer coefficients for natural and mixed convection in horizontal annuli is important for designing double pipe heat exchangers and for energy storage systems. In part one and two of this study, the 2D numerical solution of the laminar natural convection of water in six internally finned horizontal annuli has been obtained. The fins are attached to the external surface of the inner cylinder. Only the symmetrical half of the horizontal annulus with three equally spaced longitudinal divergent solid and porous fins are considered. The parameters of the problem are Rayleigh number, fin height, permeability and porosity of the porous fin, etc. The above parameters are suitably varied to ascertain their effects on fluid flow and heat transfer. The results show that traditional solid fins provide much higher heat transfer rates compared to the porous fins. Part three of this work deals with mixed convective heat transfer (laminar natural and forced convections) of water in a vented annulus. The forced flow conditions are imposed by providing an inlet at the top and an outlet at the bottom. For various parameters of the problem, the average and local Nusselt numbers along the inner cylinder are calculated for water for both aiding and opposing flows. The fourth part of this study deals with numerical modeling of natural convection of nanofluids in a horizontal cylindrical annulus. Simulations are carried out for Cu-water nanofluids. The results, in general, show that nanoparticles systematically decrease the natural convective heat transfer coefficient on the inner cylinder. Practical and useful correlations are provided for calculating average heat transfer rates from the inner cylinder in the form of average equivalent thermal conductivity and average Nusselt number for all of the four cases discussed above. These correlations are new and will be helpful in designing heat exchangers.
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Modeling the impact of a liquid droplet on a solid surfaceHealy, William M. 05 1900 (has links)
No description available.
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Onset of flow instability and critical heat flux in horizontal, thin, uniformly-heated annuliStoddard, Ryan Manse 05 1900 (has links)
No description available.
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Steady thermocapillary flow between a non-wetting liquid droplet and a solid surfaceWood, Andrea Marie 12 1900 (has links)
No description available.
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Theoretical modeling of onset of ledinegg flow instability in a heated channelRhodes, Matthew D. 05 1900 (has links)
No description available.
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Thermocapillary migration of a three-dimensional liquid droplet on a solid surfaceBenintendi, Steven William 05 1900 (has links)
No description available.
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Local convective heat transfer from heated flat plates using synthetic air jetsGillespie, Mark B. 08 1900 (has links)
No description available.
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A spectral model of bubble convection.Daley, Roger Willis January 1971 (has links)
No description available.
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