Comprehensive correlations for laminar mixed convection line plume and wall plume

Lin, H. M.; Cheng, W.C.

doi:10.1016/0017-9310(92)90115-9

Cited by 5 publications

(2 citation statements)

References 10 publications

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“…The selfsimilar analyses were extended to second-order (Hieber & Nash 1975) and third-order boundary layer theories (M6rwald et al 1986). Recently, a correlation for the centreline temperature has been developed by Lin & Cheng (1992). This correlation equation is valid over the entire buoyancy regime and for any Prandtl number.…”

Section: Introductionmentioning

confidence: 99%

Buoyant plane plumes from heated horizontal confined wires and cylinders

Lauriat

Desrayaud

1994

Sadhana

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Two-dimensional computations are reported for timedependent laminar buoyancy-induced flows above a horizontal heated source immersed in an air-filled vessel. Two kinds of heated source were considered: a line heat source, modelled as a heat source term in the energy equation, and a heat-flux cylinder of small diameter. First, comparisons are presented for the results obtained for these two heated sources. Rather large discrepencies between the velocity fields appeared in the conduction regime due to the weak plume motion, while close agreements were found in the boundary layer regime. Nevertheless, same types of bifurcations occur with almost identical frequencies, whatever the Rayleigh number. It is concluded that for dimensions of the enclosures, which largely compared with the cylinder radius, the heat source term model is a promising way to study the behaviour of unsteady plumes owing to its simplicity, flexibility, and low computational costs. Second, transitions to unsteady flows were studied through direct flow simulations for various depths of immersion of a line heat source in the central vertical plane of a vessel. Different routes to chaos were shown to occur according to the aspect ratio of the vessel and the depth of immersion of the line source. Three distinct regimes were detected with different underlying physical mechanisms called natural swaying motion, penetrative convection and Rayleigh-Benard-like convection. The first bifurcations associated with these regimes are supercritical Hopf bifurcation, pitchfork bifurcation and subcritical Hopf bifurcation. Comparisons with experimental results of confined buoyant plumes above heated wires show very good agreement with laminar frequency correlations.

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Section: Introductionmentioning

confidence: 99%

Buoyant plane plumes from heated horizontal confined wires and cylinders

Lauriat

Desrayaud

1994

Sadhana

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“…Krishnamurthy and Gebhart [11] treated this problem using the method of matched asymptotic expansions taking into account the non-boundary-layer effects. Lin and Cheng [13] presented correlation equations for predicting the centerline temperature of mixed convection plumes.…”

Section: Introductionmentioning

confidence: 99%

A note on mixed convection of laminar plane water plumes at temperatures around the density extremum

Pantokratoras

2007

Arch Appl Mech

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In all studies concerning mixed convection in plane laminar plumes a linear relationship between fluid density and temperature has been used. However, it is known that the water density-temperature relationship is non-linear at low temperatures with a density maximum at 3.98 • C for pure water. In this note the problem of plane laminar water plume in a coflowing vertical free stream has been investigated taking into account the non-linearity between density and temperature. This is the first work in the literature which treats plane mixed convection plumes with nonlinear relation between density and temperature. Both rising and descending plumes have been investigated. It was found that the ambient water temperature plays an important role on the results. When the ambient temperature is greater than maximum density temperature (T a > T m ), the water plume behavior is similar to that of the classical plume with linear density-temperature relationship. However, when the ambient temperature is equal or lower than the maximum density temperature the water plume behavior is completely different from the classical plume with linear density-temperature relationship. The centerline velocity shows a series of maxima and minima which are produced by the combination of the nonlinear density-temperature relation and the free stream.

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