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Wyszukujesz frazę "Rayleigh number" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Vertical heat transport at infinite Prandtl number for micropolar fluid
Autorzy:
Caggio, M.
Kalita, P.
Łukaszewicz, G.
Mizerski, K. A.
Powiązania:
https://bibliotekanauki.pl/articles/38611128.pdf
Data publikacji:
2020
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
micropolar fluid
Rayleigh–Benard convection
heat transport
Rayleigh number
Prandtl number
Nusselt number
Opis:
We investigate the upper bound on the vertical heat transport in the fully 3D Rayleigh–Bénard convection problem at the infinite Prandtl number for a micropolar fluid. We obtain a bound, given by the cube root of the Rayleigh number, with a logarithmic correction. The derived bound is compared with the optimal known one for the Newtonian fluid. It follows that the (optimal) upper bound for the micropolar fluid is less than the corresponding bound for the Newtonian fluid at the same Rayleigh number. Moreover, strong microrotational diffusion effects can entirely suppress the heat transfer. In the Newtonian limit our purely analytical findings fully agree with estimates and scaling laws obtained from previous theories significantly relying on phenomenology.
Źródło:
Archives of Mechanics; 2020, 72, 6; 525-553
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the onset of thermal instability of a porous medium layer saturating a Jeffrey nanofluid
Autorzy:
Rana, Gian C.
Gautam, Poonam Kumari
Powiązania:
https://bibliotekanauki.pl/articles/38883772.pdf
Data publikacji:
2022
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
nanofluid
Jeffrey model
Rayleigh number
porous medium
convection
Opis:
The onset of stationary convection in thermal instability of porous layer saturating a Jeffrey nanofluid is studied. The behaviour of nanofluid is described by a Jeffrey fluid model and the porous layer is assumed to follow Darcy’s law. Due to the presence of the Jeffrey parameter and nanoparticles, the momentum-balance equation of fluid is modified. The linear stability analysis and normal modes analysis method are utilised to derive the dispersion relation for the Rayleigh number in terms of various parameters for free-free boundaries. The effects of the Jeffrey parameter, Lewis number, modified diffusivity ratio, nanoparticles’ Rayleigh number and medium porosity on the physical system are discussed analytically and graphically.
Źródło:
Engineering Transactions; 2022, 70, 2; 123-139
0867-888X
Pojawia się w:
Engineering Transactions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anisotropic turbulent viscosity and large-scale motive force in thermally driven turbulence at low Prandtl number
Autorzy:
Mizerski, K. A.
Powiązania:
https://bibliotekanauki.pl/articles/38695701.pdf
Data publikacji:
2022
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
thermal convection
heat transport
Rayleigh number
Prandtl number
random heat source
Opis:
The fully developed turbulent Boussinesq convection is known to form large-scale rolls, often termed the ‘large-scale circulation’ (LSC). It is an interesting question how such a large-scale flow is created, in particular in systems when the energy input occurs at small scales, when inverse cascade is required in order to transfer energy into the large-scale modes. Here, the small-scale driving is introduced through stochastic, randomly distributed heat source (say radiational). The mean flow equations are derived by means of simplified renormalization group technique, which can be termed a ‘weakly nonlinear renormalization procedure’ based on consideration of only the leading order terms at each step of the recursion procedure, as full renormalization in the studied anisotropic case turns out unattainable. The effective, anisotropic viscosity is obtained and it is shown that the inverse energy cascade occurs via an effective ‘motive force’ which takes the form of transient negative, vertical diffusion.
Źródło:
Archives of Mechanics; 2022, 74, 5; 409-436
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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