Unsteady multicellular natural convection in a narrow horizontal cylindrical annulus

Fant, D. B.; Prusa, Joseph M.; Rothmayer, A. P.

doi:10.2514/6.1988-3775

Cited by 4 publications

(3 citation statements)

References 21 publications

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“…Chung et al (1999) obtained a tetracellular solution at very high Rayleigh numbers for R = 1.2. A few authors have studied natural convection in narrow-gap annuli numerically for very small Prandtl numbers or the limiting case of zero Prandtl number (Fant et al 1990(Fant et al , 1991Yoo, Choi & Kim 1994). For these cases, hydrodynamic-type instabilities originate in the two side regions of the annulus, similar to natural convection in a vertical cavity of large aspect ratio.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional natural convective states in a narrow-gap horizontal annulus

Dyko

Vafai

2001

J. Fluid Mech.

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Buoyancy-driven flow in a narrow-gap annulus formed by two concentric horizontal cylinders is investigated numerically. The three-dimensional transient equations of fluid motion and heat transfer are solved to study multiple supercritical states occurring within annuli having impermeable endwalls, which are encountered in various applications. For the first time, three-dimensional supercritical states are shown to occur in a narrow-gap annulus and the existence of four such states is established. These four states are characterized by the orientations and directions of rotation of counter-rotating rolls that form in the upper part of the annulus owing to thermal instability, and exhibit (i) transverse rolls, (ii) transverse rolls with reversed directions of rotation, (iii) longitudinal rolls in combination with transverse rolls, and (iv) longitudinal rolls with reversed directions of rotation in combination with transverse rolls, respectively. Simulations are performed at Rayleigh numbers approaching and exceeding the critical value to gain insight into the physical processes influencing development of the secondary flow structures. The evolution of the supercritical flow fields and temperature distributions with increasing Rayleigh number and the interaction between the secondary and primary flows are thoroughly investigated. Factors influencing the number of rolls are studied for each supercritical state. Heat transfer results are presented in the form of local Nusselt number distributions and overall annulus Nusselt numbers. Two-dimensional natural convection occurring early in the transient evolution of the flow field is also examined. Results obtained for a wide range of annulus radius ratios and Rayleigh numbers are shown to be in excellent agreement with results from previous experimental and numerical studies, thereby validating the present numerical scheme.

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Section: Introductionmentioning

confidence: 99%

Three-dimensional natural convective states in a narrow-gap horizontal annulus

Dyko

Vafai

2001

J. Fluid Mech.

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“…These consist either in the birth of co-rotating steady cells, or in the insurgence of traveling-wave oscillations. Fant et al [50] performed stability analyses of the flow in a two-dimensional annulus in the limit Pr/0, where convective effects become negligible in the energy equation. Numerical solutions of both the boundary layer equations, and the full Naviere Stokes equations were used for linear analyses.…”

Section: The Low-prandtl Number Rangementioning

confidence: 99%

A critical review of buoyancy-induced flow transitions in horizontal annuli

Angeli

Barozzi

Collins

et al. 2010

International Journal of Thermal Sciences

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“…Kuehn et al investigated the velocity and temperature distributions and local heat-transfer coefficients for natural convection within a horizontal annulus [3]. Fant et al investigated the unsteady multicellular natural convection at the high Ar [4]. Yoo studied the natural convection in a narrow horizontal cylindrical annulus at low Prandtl numbers [5].…”

Section: Introductionmentioning

confidence: 98%

Study of multiple steady solutions for the 2D natural convection in a concentric horizontal annulus with a constant heat flux wall using immersed boundary-lattice Boltzmann method

Shu

et al. 2015

International Journal of Heat and Mass Transfer

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Unsteady multicellular natural convection in a narrow horizontal cylindrical annulus

Cited by 4 publications

References 21 publications

Three-dimensional natural convective states in a narrow-gap horizontal annulus

Three-dimensional natural convective states in a narrow-gap horizontal annulus

A critical review of buoyancy-induced flow transitions in horizontal annuli

Study of multiple steady solutions for the 2D natural convection in a concentric horizontal annulus with a constant heat flux wall using immersed boundary-lattice Boltzmann method

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