scholarly journals Stellar Convection as a Low Prandtl Number Flow

1991 ◽  
Vol 130 ◽  
pp. 57-61
Author(s):  
Josep M. Massaguer
Keyword(s):  
Nusselt Number ◽  
Prandtl Number ◽  
Heat Transport ◽  
Large Scale ◽  
Shear Layers ◽  
Turbulent Convection ◽  
The Sun ◽  
Stellar Convection ◽  
Cool Stars ◽  
Number Flow

AbstractThermal convection in the Sun and cool stars is often modeled with the assumption of an effective Prandtl number σ ≃ 1. Such a parameterization results in masking of the presence of internal shear layers which, for small σ, might control the large scale dynamics. In this paper we discuss the relevance of such layers in turbulent convection. Implications for heat transport – i.e. for the Nusselt number power law – are also discussed.

Improved Modeling of Near-Wall Heat Transport for Cooling of Electric and Hybrid Powertrain Components by High Prandtl Number Flow

2017 ◽  
Vol 10 (3) ◽  
pp. 778-784
Author(s):  
Sanjin Saric ◽  
Andreas Ennemoser ◽  
Branislav Basara ◽  
Heinz Petutschnig ◽  
Christoph Irrenfried ◽  
...  
Keyword(s):  
Prandtl Number ◽  
Heat Transport ◽  
Hybrid Powertrain ◽  
Number Flow ◽  
High Prandtl Number ◽  
Near Wall

scholarly journals On Estimating Fluxes due to Small-Scale Turbulent Convection in a Rotating Star

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
D. O. Gough
Keyword(s):  
Large Scale ◽  
Convection Zone ◽  
Turbulent Fluxes ◽  
Turbulent Convection ◽  
Small Scale ◽  
The Sun ◽  
Mixing Length ◽  
Large Scale Flow ◽  
Rotating Star ◽  
The Way

The way in which turbulent fluxes are usually represented in computations of large-scale flow in the convection zones of the sun and other stars is briefly described. A model of an ensemble of eddies that is capable of generalization to circumstances more complicated than the usual essentially spherically symmetrical convection zone is outlined. Generalization usually requires the introduction of new postulates, and, in so doing, also lays bare some of the assumptions, often implicit, in the usual mixing-length formalisms.

scholarly journals Counter-gradient heat transport in two-dimensional turbulent Rayleigh–Bénard convection

2013 ◽  
Vol 737 ◽  
Author(s):  
Yong-Xiang Huang ◽  
Quan Zhou
Keyword(s):  
Prandtl Number ◽  
Heat Transport ◽  
Large Scale ◽  
Three Dimensional ◽  
Local Heat ◽  
Two Dimensional ◽  
Number Range ◽  
Local Heat Flux ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

AbstractWe present high-resolution numerical investigations of heat transport by two-dimensional (2D) turbulent Rayleigh–Bénard (RB) convection over the Rayleigh number range $1{0}^{8} \leqslant Ra\leqslant 1{0}^{10} $ and the Prandtl number range $0. 7\leqslant Pr\leqslant 10$. We find that there exists strong counter-gradient local heat flux with magnitude much larger than the global Nusselt number $Nu$ of the system. Two mechanisms for generating counter-gradient heat transport are identified: one is due to the bulk dynamics and the other is due to the competition between the corner-flow rolls and the large-scale circulation (LSC). While the magnitude of the former is found to increase with increasing Prandtl number, that of the latter maximizes at medium $Pr$. We further reveal that the corner–LSC competition leads to the anomalous $Nu$–$Pr$ relation in 2D RB convection, i.e. $Nu(Pr)$ minimizes, rather than maximizes as in the three-dimensional cylindrical case, at $Pr\approx 2\sim 3$ for moderate $Ra$.

scholarly journals The Quest to Understand Supergranulation and Large-Scale Convection in the Sun

Solar Physics ◽  
2014 ◽  
Vol 289 (9) ◽  
pp. 3403-3419 ◽  
Author(s):  
Shravan M. Hanasoge ◽  
Katepalli R. Sreenivasan
Keyword(s):  
Large Scale ◽  
The Sun

Turbulent convection driven by surface cooling in shallow water

2002 ◽  
Vol 464 ◽  
pp. 81-111 ◽  
Author(s):  
OLEG ZIKANOV ◽  
DONALD N. SLINN ◽  
MANHAR R. DHANAK
Keyword(s):  
Thermal Convection ◽  
Large Scale ◽  
Fourier Method ◽  
Vertical Direction ◽  
Finite Depth ◽  
Turbulent Convection ◽  
Bottom Surface ◽  
Computational Domain ◽  
Surface Cooling ◽  
Adverse Weather

We present the results of large-eddy simulations (LES) of turbulent thermal convection generated by surface cooling in a finite-depth stably stratified horizontal layer with an isothermal bottom surface. The flow is a simplified model of turbulent convection occurring in the warm shallow ocean during adverse weather events. Simulations are performed in a 6 × 6 × 1 aspect ratio computational domain using the pseudo-spectral Fourier method in the horizontal plane and finite-difference discretization on a high-resolution clustered grid in the vertical direction. A moderate value of the Reynolds number and two different values of the Richardson number corresponding to a weak initial stratification are considered. A version of the dynamic model is applied as a subgrid-scale (SGS) closure. Its performance is evaluated based on comparison with the results of direct numerical simulations (DNS) and simulations using the Smagorinsky model. Comprehensive study of the spatial structure and statistical properties of the developed turbulent state shows some similarity to Rayleigh–Bénard convection and other types of turbulent thermal convection in horizontal layers, but also reveals distinctive features such as the dominance of a large-scale pattern of descending plumes and strong turbulent fluctuations near the surface.

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