Experimental study of the forces associated with mixed convection from a heated sphere at small Reynolds and Grashof numbers. Part II: Assisting and opposing flows

Mograbi, Elaad; Ziskind, G.; Katoshevski, David; Bar‐Ziv, Ezra

doi:10.1016/s0017-9310(01)00350-7

Cited by 20 publications

(7 citation statements)

References 10 publications

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“…Grashof number, 4gb(T s À T 1 )R 3 on the forces experienced by a heated sphere in mixed convection either due to a cross-flow or vertical flows are reported in the papers by Ziskind et al [24] and Mograbi et al [25] for small values of Reynolds number and Grashof number. Mograbi and Bar-Ziv [26,27] presented a combined numerical and experimental study on steady state mixed convection around a small spherical particle in the diameter range of 10-200 for small values of Reynolds, 0-0.3, and Grashof number in the range 0-0.1.…”

Section: Introductionmentioning

confidence: 89%

Mixed convection from an isolated spherical particle

Bhattacharyya

Singh

2008

International Journal of Heat and Mass Transfer

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Section: Introductionmentioning

confidence: 89%

Mixed convection from an isolated spherical particle

Bhattacharyya

Singh

2008

International Journal of Heat and Mass Transfer

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“…Tang and Johnson (1990) obtained various flow patterns of opposing flow by mixed convection experiments with a Grashof number of 9.0 × 10 5 and Reynolds numbers up to 1100 [8]. Recently, Ziskind et al (2001) and Mograbi et al (2002) studied the cross-flow, assisting and opposing flows at low Grashof number and Reynolds number in an electrodynamics chamber (EDC) [9,10]. Koizumi (2004) studied the time and spatial heat transfer performance around an isothermal sphere in a uniform, downwardly directed air flow by conducting an experiments with Grashof number of Gr = 3.3 × 10 5 and Reynolds numbers up to 1800 [11].…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on the Mixed Convection Heat Transfer between a Sphere Particle and High Pressure Water in Pseudocritical Zone

Wei

2013

Advances in Mechanical Engineering

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Mixed convection heat transfer between supercritical water and particles is a major basic problem in supercritical water fluidized bed reactor, but little work focused on this new area in the past. In this paper, a numerical model fully accounting for thermophysical property variation has been established to investigate heat transfer between supercritical water and a single spherical particle under gravity. Flow field, temperature field and Nusselt number are analyzed based on the simulation results. Results show that buoyancy force has a remarkable effect on flow and heat transfer process. When the direction of gravity and flow are opposite, the gravity enhances the heat transfer before the separation point and inhibits the heat transfer after the separation point. When gravity is incorporated in calculation, a higher temperature gradient and a thinner boundary layer in the vicinity of the particle surface are observed before separation point, and the situations are just the reverse after separation point. Variation of specific heat and conductivity plays a main role in determination of heat transfer coefficient.

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“…Experimental investigations concern mostly both the assisting and opposing flows past a sphere. The work by Yuge (1960), Klyachko (1963), Katoshevski et al (2001), , Mograbi et al (2002) and Mograbi & Bar-Ziv (2005a, b) focused mainly on acquisition of data concerning the drag and heat flux (drag coefficient and Nusselt number). Work investigating details of the flow is less common (see Tang & Johnson 1990).…”

Section: Introductionmentioning

confidence: 99%

Transition to turbulence in the wake of a fixed sphere in mixed convection

2009

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International audienceThe thermal effect on axisymmetry breaking and transition to turbulence in the wake of a fixed heated sphere is investigated in the mixed convection configurations commonly known as 'assisting'and 'opposing' flows in which the buoyancy tends, respectively, to accelerate and decelerate the flow. The study is carried out in the Ri –Re parameter plane (Ri being the mixed convection parameter – the Richardson number) for two values of Prandtl number – 0.72 (≈air and many gases) and 7 (≈water). We show that convection affects considerably the transition (as compared to that observed in the wake of an unheated sphere) even at moderate Richardson numbers. The latter are taken to be positive in assisting flow and negative in opposing one. In this notation, it can be said that convection shifts the primary-instability threshold to higher Reynolds numbers with increasing Richardson number. In assisting flow, the primary bifurcation is always regular, but at Ri > 0.6 it appears in azimuthal subspaces associated with higher azimuthal wavenumbers m > 1. The transition scenario is characterized by a large variety of regimes explainable by nonlinear interactions between different azimuthal subspaces. On the side of higher (positive) Richardson numbers the axisymmetric flow is found stable up to Re = 1400 at Pr = 0.72 and Ri = 0.7. In opposing flow, the m = 1 subspace is always the most unstable, but the regular bifurcation gives way to a Hopf one at Ri < −0.1. Close to the junction of both bifurcations a similar variety of regimes precedes the transition to chaos as in assisting flow. On the side of negative Richardson numbers the primary (Hopf) bifurcation threshold is found as low as Re = 100 at Ri = −0.25 and at both investigated Prandtl numbers. After a primary periodic regime characterized by vortex shedding with a symmetry plane, the transition proceeds via a series of increasingly irregular helical regimes

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Experimental study of the forces associated with mixed convection from a heated sphere at small Reynolds and Grashof numbers. Part II: Assisting and opposing flows

Cited by 20 publications

References 10 publications

Mixed convection from an isolated spherical particle

Mixed convection from an isolated spherical particle

Numerical Study on the Mixed Convection Heat Transfer between a Sphere Particle and High Pressure Water in Pseudocritical Zone

Transition to turbulence in the wake of a fixed sphere in mixed convection

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