Etude expérimentale de la convection mixte entre deux plans horizontaux à températures différentes—II

Ouazzani, M. T.; Platten, J. K.; Mojtabi, Abdelkader

doi:10.1016/0017-9310(90)90039-w

Cited by 70 publications

(34 citation statements)

References 21 publications

(11 reference statements)

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“…Similar patterns also appear in the Taylor-Couette system with an axial throughfiow [21,22]. In recent experimental work on Rayleigh-Benard convection with throughffow competition between longitudinal and transversal rolls [13,23] has been observed; also a superposition of both structures and more complicated timedependent behavior is possible. This competitive dynamics has been investigated by Brand, Ahlers, and Deissler [24] with a phenomenological model of two coupled amplitude equations for transversal and longitudinal rolls which, however, di6'er from the more rigorously derived equations [25].…”

Section: Introductionmentioning

confidence: 55%

Transversal convection patterns in horizontal shear flow

1992

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We investigate the influence of a horizontal plane Poiseuille shear flow transversal to the convective roll chain of the Rayleigh-Benard problem. Using a one-dimensional (1D) amplitude equation and a 2D numerical simulation of the basic field equations, we study how different boundary conditions at the inlet and outlet of the channel affect nonlinear convection. If convection is suppressed near the cell apertures, spatially localized traveling-wave states appear with a uniquely selected bulk wavelength. For convectively unstable parameters this pattern is pushed out of the channel; however, the system becomes very sensitive to perturbations, and noise-driven structures occur. Phase-pinning boundary conditions lead for very small flows to stationary roll patterns with a space-dependent wavelength decreasing downstream. Strengthening the throughflow causes local Eckhaus instabilities, which finally generate a transition to propagating rolls.PACS number(s): 47.20. 8p, 47.20.Ky, 47.60.+i

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Section: Introductionmentioning

confidence: 55%

Transversal convection patterns in horizontal shear flow

1992

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“…Later on, Luijkx et al 9 have demonstrated the existence of transverse rolls parallel to the flow direction for which the critical Rayleigh number increases when Reynolds number increases. Several experimental and numerical investigations were carried out to determine the conditions of transverse roll onset in a rectangular channel 3,10,11 . They also proved that the critical Rayleigh number of the appearance of the transverse rolls depends on the Prandtl number and the aspect ratio of the channel.…”

Section: Introductionmentioning

confidence: 97%

Linear stability analysis of mixed convection flow in a horizontal channel filled with nanofluids

et al. 2020

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The convective instability driven by buoyancy in the Poiseuille-Rayleigh-Bénard flow through two infinite parallel horizontal plates filled with nanofluids is investigated using linear stability analysis. We considered water-based nanofluids with different volume fractions of aluminum (Al O 2 3 ) and silver (Ag) nanoparticles. A spectral collocation method founded on Chebyshev polynomials is implemented and the obtained algebraic eigenvalue problem is solved. In this study, we have numerically determined the critical Rayleigh number of the onset of longitudinal and transversal rolls and the results are represented in the form of marginal stability curves. Critical wave numbers that describe the size of convective cells in the flow are also presented, analyzed, and compared with those of the Poiseuille-Rayleigh-Bénard flow without nanoparticles. The effects of the type and nanoparticle volume fractions on the onset of both longitudinal and transversal rolls are investigated. K E Y W O R D S mixed convection, nanofluids, Poiseuille-Rayleigh-Bénard, thermoconvective instabilities

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“…Thus the stability diagrams of PRB flows present many flow configurations. A few examples, established experimentally, theoretically and numerically, for different Prandtl numbers and aspect ratios, can be found in [6][7][8][9] in the case of pure fluids. In the case of air PRB flows (Pr=0.7), a complete stability diagram at B≥10 is presented in [10].…”

Section: Introductionmentioning

confidence: 99%