Etude numérique et expérimentale de la convection mixte entre deux plans horizontaux à températures différentes

Ouazzani, M. T.; Caltagirone, J.-P.; Meyer, Georg; Mojtabi, Abdelkader

doi:10.1016/0017-9310(89)90173-7

Cited by 55 publications

(19 citation statements)

References 6 publications

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“…The extrapolated phase speed at Re = 0 compares reasonably well with the values of around 1.4 reported by Ouazzani, Caltagirone, Meyer & Mojtabi (1989) and Nicolas et al (2000). The physical reason for this strong effect of Re is the small thermal diffusion velocity in the wall (α wall /2d) based on approximately one roll wavelength (≈2d) which, for water at Ra = 4000, is smaller than the flow velocity beyond Re ≈ 0.013 and therefore acts as a 'brake' on the propagation of TRs.…”

Section: Appearance Of Transverse Rolls At the Convective-absolute Bosupporting

confidence: 86%

Experimental investigation into localized instabilities of mixed Rayleigh–Bénard–Poiseuille convection

Grandjean

Monkewitz

2009

J. Fluid Mech.

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The stability of the Rayleigh–Bénard–Poiseuille flow in a channel with large transverse aspect ratio (ratio of width to vertical channel height) is studied experimentally. The onset of thermal convection in the form of ‘transverse rolls’ (rolls with axes perpendicular to the Poiseuille flow direction) is determined in the Reynolds–Rayleigh number plane for two different working fluids: water and mineral oil with Prandtl numbers of approximately 6.5 and 450, respectively. By analysing experimental realizations of the system impulse response it is demonstrated that the observed onset of transverse rolls corresponds to their transition from convective to absolute instability. Finally, the system response to localized patches of supercriticality (in practice local ‘hot spots’) is observed and compared with analytical and numerical results of Martinand, Carrière & Monkewitz (J. Fluid Mech., vol. 502, 2004, p. 175 and vol. 551, 2006, p. 275). The experimentally observed two-dimensional saturated global modes associated with these patches appear to be of the ‘steep’ variety, analogous to the one-dimensional steep nonlinear modes of Pier, Huerre & Chomaz (Physica D, vol. 148, 2001, p. 49).

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Section: Appearance Of Transverse Rolls At the Convective-absolute Bosupporting

confidence: 86%

Experimental investigation into localized instabilities of mixed Rayleigh–Bénard–Poiseuille convection

Grandjean

Monkewitz

2009

J. Fluid Mech.

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“…Stability diagram of the thermoconvective patterns of PRB flows at Pr = 0.7 and B ≥ 10, built from the experimental, [19][20][21] numerical, 26 and linear stability, 6,7,10,16 results and the present linear stability and numerical results. Bold lines are for theoretical results, open symbols for experimental results, and solid symbols for the present results.…”

Section: Ramentioning

confidence: 99%

“…VII. Ra // *=1728.83, B=10 [16] Ra ⊥ *, B →∞ [6] Ra ⊥ c/a , B→∞ [7] R ⊥ , B=12 [20] R ⊥ /R // transition, B=19.5 [19] R mix /R // transition, B=12 [20] R mix /R // transition, B=10 [21] Ra osc *, B →∞ [10] Ra ≈ *, B →∞ [10] Ra ≈ *, pres. linear stab., B=10 R // or R ≈ , pres.…”

Section: Introductionmentioning

confidence: 99%

Influence of a white noise at channel inlet on the parallel and wavy convective instabilities of Poiseuille-Rayleigh-Bénard flows

2012

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“…The systematic error of about 0.5% is a result of the discretization density in the finite di6'erence algorithm; it reduces if the spatial and temporal resolution is improved. Equation (5.5) yields the theoretical explanation for the observation[18] that the pattern propagation velocity decreases linearly with the Rayleigh number if the flow rate Re is held fixed.…”

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confidence: 99%

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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Etude numérique et expérimentale de la convection mixte entre deux plans horizontaux à températures différentes

Cited by 55 publications

References 6 publications

Experimental investigation into localized instabilities of mixed Rayleigh–Bénard–Poiseuille convection

Experimental investigation into localized instabilities of mixed Rayleigh–Bénard–Poiseuille convection

Influence of a white noise at channel inlet on the parallel and wavy convective instabilities of Poiseuille-Rayleigh-Bénard flows

Transversal convection patterns in horizontal shear flow

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