Temporal dynamics of large-scale structures for turbulent Rayleigh–Bénard convection in a moderate aspect-ratio cylinder

Sakievich, Philip; Peet, Yulia; Adrian, Ronald J.

doi:10.1017/jfm.2020.588

Cited by 9 publications

(9 citation statements)

References 56 publications

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“…This rough characterization of the flow structure is consistent with the distributions of the vertical velocity component in figures 5(c) and 5(d). The appearance of finer structures in the velocity contours illustrates the character of inertia-dominated fluid turbulence and is in line with previous studies (Pandey et al 2018;Vogt et al 2018a;Krug et al 2020;Sakievich et al 2020) which demonstrated the occurrence of more small-scale velocity fluctuations compared with the temperature field. Thus, it can be stated that the results of the numerical simulations confirm the mean flow structure of the cellular regime suggested from the experiment based on a limited number of velocity sensors (Akashi et al 2019).…”

Section: Experimental Set-upsupporting

confidence: 91%

“…In this general respect, our study is comparable to the work of Sakievich et al (2016Sakievich et al ( , 2020, although the observed flow patterns differ from each other, which we believe is due to the differences in the shape of the convection vessels (cylinder versus box). In particular, it is not surprising that the flow in the box is restricted in its dynamics and does not form a rotational symmetry as shown by Sakievich et al (2020). The cellular flow regime, instead, shows mirror symmetry with respect to the two vertical centre planes x = 2.5 and y = 2.5 of the convection box, respectively.…”

Section: Discussionsupporting

confidence: 79%

“…Numerical studies identified the typical sizes of turbulent superstructures in large aspect ratios Γ > 10, which are of the order of 10H for Pr = 6.7 (Busse 1994;Pandey et al 2018) or 6H to 7H for Pr = 0.7 (Hartlep et al 2003;Pandey et al 2018;Stevens et al 2018). Sakievich et al (2016Sakievich et al ( , 2020 refer to these 'natural' dimensions of superstructures to explain the dominance of specific Fourier modes in a flat Γ = 6.3 cylinder at Pr = 6.7. From the data published by Pandey et al (2018), it is evident that the horizontal wavelength of the superstructures in the range Pr 10 decreases when approaching smaller Pr.…”

Section: Discussionmentioning

confidence: 99%

“…showed that the thermal updrafts and downdrafts match the three-dimensional field to a high degree in a Γ = 6.3 cylinder. Further analysis bySakievich et al (2020) revealed a high correlation in the…”

mentioning

confidence: 93%

“…The authors suggest an analogy to the 'wind of turbulence' occurring in RBC at low aspect ratios. A further study by Sakievich et al (2020) provides a continuation of the characterization of this particular regime by Fourier modal decomposition and by an extension of the total run time of the simulations covering more than 3000 free-fall times. The authors showed that compared to the standard case at Γ = 1, the flow dynamics covers much longer time scales of the order of hundreds to thousands of free-fall times.…”

Section: Introductionmentioning

confidence: 99%

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Jump rope vortex flow in liquid metal Rayleigh–Bénard convection in a cuboid container of aspect ratio

et al. 2021

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We study the topology and the temporal dynamics of turbulent Rayleigh–Bénard convection in a liquid metal with a Prandtl number of 0.03 located inside a box with a square base area and an aspect ratio of $\varGamma = 5$ . Experiments and numerical simulations are focused on the Rayleigh number range $6.7 \times 10^{4} \leqslant Ra \leqslant 3.5 \times 10^{5}$ , where a new cellular flow regime has been reported previously (Akashi et al., Phys. Rev. Fluids, vol. 4, 2019, 033501). This flow structure shows symmetries with respect to the vertical planes crossing at the centre of the container. The dynamic behaviour is dominated by strong three-dimensional oscillations with a period length that corresponds to the turnover time. Our analysis reveals that the flow structure in the $\varGamma = 5$ box corresponds in key features to the jump rope vortex structure, which has recently been discovered in a $\varGamma = 2$ cylinder (Vogt et al., Proc. Natl Acad. Sci. USA, vol. 115, 2018, pp. 12674–12679). While in the $\varGamma = 2$ cylinder a single jump rope vortex occurs, the coexistence of four recirculating swirls is detected in this study. Their approach to the lid or the bottom of the convection box causes a temporal deceleration of both the horizontal velocity at the respective boundary and the vertical velocity in the bulk, which in turn is reflected in Nusselt number oscillations. The cellular flow regime shows remarkable similarities to properties commonly attributed to turbulent superstructures.

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