Scalings for unsteady natural convection boundary layer under time-varying heating flux in a small Prandtl number fluid

Lin, Wenxian, Armfield, S.W., and Khatamifar, Mehdi (2021) Scalings for unsteady natural convection boundary layer under time-varying heating flux in a small Prandtl number fluid. Case Studies in Thermal Engineering, 27. 101351.

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Abstract

The unsteady natural convection boundary layer (NCBL) on a vertical wall heated by time varying flux in initially quiescent homogeneous fluid with a small Prandtl number (Pr) was studied. Scalings for the parameters typifying NCBL behavior, including plate temperature, maximum vertical velocity, thermal boundary-layer thickness, and velocity boundary-layer thickness, at different development stages, and the time for the transition from the start-up stage to the quasi-steady state, were developed by scaling analysis. The obtained scalings were compared to and validated by the numerical results with different values of Pr, the Rayleigh number Ra and the dimensionless time-varying heat flux frequency fn, over 106 ≤ Ra ≤ 109, 0.01 ≤ Pr ≤ 0.5, and 0.001 ≤ fn ≤ 0.025. It is also found that the development of the boundary layer at the start-up stage is one-dimensional and but becomes two-dimensional at the quasi-steady state.

Item ID: 69442
Item Type: Article (Research - C1)
ISSN: 2214-157X
Keywords: Natural convection; Boundary layer; Scaling; Time-varying heat flux; Small Prandtl number
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Copyright Information: The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.
Funders: Australian Research Council (ARC)
Projects and Grants: ARC DP130100900
Date Deposited: 28 Sep 2021 22:40
FoR Codes: 40 ENGINEERING > 4012 Fluid mechanics and thermal engineering > 401207 Fundamental and theoretical fluid dynamics @ 50%
40 ENGINEERING > 4012 Fluid mechanics and thermal engineering > 401204 Computational methods in fluid flow, heat and mass transfer (incl. computational fluid dynamics) @ 50%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280110 Expanding knowledge in engineering @ 100%
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