Poster: Turbulent Horizontal Convection at High Prandtl Numbers

Passaggia, Pierre-Yves; Hurley, Matthew W.; White, Brian; Scotti, Alberto

doi:10.1103/aps.dfd.2016.gfm.p0028

Cited by 2 publications

(3 citation statements)

References 20 publications

(64 reference statements)

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“…The ∼Ra 1/5 scaling seems to persist up to our highest Ra for Pr = 0.1. Regime II l of the SGL model was not observed in our DNS, because Pr = 0.1 is still too large for this regime (Passaggia, Scotti & White 2018). For Pr = 1 and 10, the curves rise again at higher Ra, leading to a scaling exponent of approximately 0.24 and 0.23.…”

Section: R1-4mentioning

confidence: 69%

“…The former seem to be dominant in wider cells, as found by Sukhanovsky et al (2012), whereas the latter seems to be most relevant for no-slip BC in narrow cells. Sheard & King (2011) found that the onset to unsteady flows is independent of vertical confinement for 0.16 Γ 2, and Passaggia et al (2018) observed the maximum growth for the 2-D plume instabilities at Γ = 6. HC instability was studied also for the cases of a BL synthetic jet (Leigh, Tsai & Sheard 2016), 2-D HC ) and different temperature BCs (Tsai et al 2020).…”

Section: Dynamics: Plumes and Oscillationsmentioning

confidence: 99%

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Classical and symmetrical horizontal convection: detaching plumes and oscillations

Reiter

Shishkina

2020

J. Fluid Mech.

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Classical and symmetrical horizontal convection is studied by means of direct numerical simulations for Rayleigh numbers Ra up to 3 × 10 12 and Prandtl numbers Pr = 0.1, 1 and 10. For both set-ups, a very good agreement in global quantities with respect to heat and momentum transport is attained. Similar to Shishkina & Wagner (Phys. Rev. Lett., vol. 116, 2016, 024302), we find Nusselt number Nu versus Ra scaling transitions in a region 10 8 Ra 10 11 . Above a critical Ra, the flow undergoes either a steady-oscillatory transition (small Pr) or a transition from steady state to a transient state with detaching plumes (large Pr). The onset of the oscillations takes place at Ra Pr −1 ≈ 5 × 10 9 and the onset of detaching plumes at Ra Pr 5/4 ≈ 9 × 10 10 . These onsets coincide with the onsets of scaling transitions.

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Section: R1-4mentioning

confidence: 69%

Section: Dynamics: Plumes and Oscillationsmentioning

confidence: 99%

Classical and symmetrical horizontal convection: detaching plumes and oscillations

Reiter

Shishkina

2020

J. Fluid Mech.

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“…Under these assumptions, the density ρ is given by ρ = ρ 0 (1 + αT), where T is the quantity that describes the stratifying agent and ρ 0 is a reference density. In experiments involving water, stratification is normally controlled either via changes in temperature, in which case α is the (negative) coefficient of thermal expansion (Niemela et al 2000;Roche et al 2002;Mullarney, Griffiths & Hughes 2004), or via varying the concentration of a salt (Stewart et al 2012;Passaggia et al 2017), and α is the positive haline contraction coefficient. Since, from a theoretical point of view, the precise nature of the stratifying agent is irrelevant, we describe stratification in terms of the buoyancy b ≡ g(ρ 0 − ρ)/ρ 0 , where g is the acceleration of gravity.…”

Section: Problem Set-upmentioning

confidence: 99%

Transition and turbulence in horizontal convection: linear stability analysis

2017

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The linear instability mechanisms of horizontal convection in a rectangular cavity forced by a horizontal buoyancy gradient along its surface are investigated using local and global stability analyses for a Prandtl number equal to unity. The results show that the stability of the base flow, a steady circulation characterized by a narrow descending plume and a broad upwelling region, depends on the Rayleigh number, $Ra$. For free-slip boundary conditions at a critical value of $Ra\approx 2\times 10^{7}$, the steady base flow becomes unstable to three-dimensional perturbations, characterized by counter-rotating vortices originating within the plume region. A Wentzel–Kramers–Brillouin (WKB) method applied along closed streamlines demonstrates that this instability is of a Rayleigh–Taylor type and can be used to accurately reconstruct the global instability mode. In the case of no-slip boundary conditions, the base flow also becomes unstable to a self-sustained two-dimensional instability whose critical Rayleigh number is $Ra\approx 1.7\times 10^{8}$. Beyond this critical $Ra$, two-dimensional equilibrium stationary states of the Navier–Stokes equations are computed using the selective frequency damping method. The two-dimensional onset of instability is shown to be characterized by a family of modes also originating within the plume. A local spatio-temporal stability analysis shows that the flow becomes absolutely unstable at the origin of the plume. Taken together, these results illustrate the mechanisms behind the onset of turbulence that has been observed in horizontal convection.

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Poster: Turbulent Horizontal Convection at High Prandtl Numbers

Cited by 2 publications

References 20 publications

Classical and symmetrical horizontal convection: detaching plumes and oscillations

Classical and symmetrical horizontal convection: detaching plumes and oscillations

Transition and turbulence in horizontal convection: linear stability analysis

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