Unsteady thermal boundary-layer on an infinite yawed wedge whose temperature gradient is prescribed

1973 ◽  
Vol 77 (5) ◽  
pp. 239-254
Author(s):  
Maharaj Singh ◽  
G. N. Sarma
Keyword(s):  
Boundary Layer ◽  
Temperature Gradient ◽  
Thermal Boundary Layer

A scaling analysis of transient natural convection in a reservoir model induced by iso-flux heating

2014 ◽  
Vol 764 ◽  
pp. 219-249 ◽  
Author(s):  
Peng Yu ◽  
John C. Patterson ◽  
Chengwang Lei
Keyword(s):  
Boundary Layer ◽  
Natural Convection ◽  
Temperature Gradient ◽  
Water Depth ◽  
Thermal Boundary Layer ◽  
Scaling Analysis ◽  
Horizontal Temperature Gradient ◽  
Reservoir Model ◽  
Transient Behaviour ◽  
Final Steady State

AbstractThis study presents a detailed scaling analysis quantifying the transient behaviour of natural convection in a reservoir model induced by iso-flux surface heating. It is found that horizontal conduction, which has often been neglected in previous analyses, plays an important role in the development of the flow. Depending on the Rayleigh number, three possible pathways through which the flow develops towards the final steady state are identified. A thermal boundary layer initially grows downwards from the surface. When the thermal boundary layer reaches the sloping bottom and becomes indistinct, a horizontal temperature gradient establishes due to the increasing water depth in the offshore direction. A flow is then driven towards the offshore direction by a buoyancy-induced horizontal pressure gradient, which convects away the heat input from the water surface. On the other hand, the horizontal temperature gradient also conducts heat away. The flow behaviour is determined by the interaction between the horizontal conduction and convection. An interesting flow feature revealed by the present scaling analysis is that the region across which the thermal boundary layer encompasses the full water depth shrinks over time at a certain stage of the flow development. The shrinking process eventually stops when this region coincides with a conduction-dominated subregion. The present scaling results are verified by corresponding numerical simulations.

Effect of Nanofluid on Heat Transfer Enhancement for Mixed Convection Flow Over a Corrugated Surface

2020 ◽  
Vol 45 (4) ◽  
pp. 373-383
Author(s):  
Nepal Chandra Roy ◽  
Sadia Siddiqa
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Local Nusselt Number ◽  
Richardson Number ◽  
Thermal Boundary Layer ◽  
Volume Fraction ◽  
Convection Flow ◽  
Mixed Convection Flow

AbstractA mathematical model for mixed convection flow of a nanofluid along a vertical wavy surface has been studied. Numerical results reveal the effects of the volume fraction of nanoparticles, the axial distribution, the Richardson number, and the amplitude/wavelength ratio on the heat transfer of Al2O3-water nanofluid. By increasing the volume fraction of nanoparticles, the local Nusselt number and the thermal boundary layer increases significantly. In case of \mathrm{Ri}=1.0, the inclusion of 2 % and 5 % nanoparticles in the pure fluid augments the local Nusselt number, measured at the axial position 6.0, by 6.6 % and 16.3 % for a flat plate and by 5.9 % and 14.5 %, and 5.4 % and 13.3 % for the wavy surfaces with an amplitude/wavelength ratio of 0.1 and 0.2, respectively. However, when the Richardson number is increased, the local Nusselt number is found to increase but the thermal boundary layer decreases. For small values of the amplitude/wavelength ratio, the two harmonics pattern of the energy field cannot be detected by the local Nusselt number curve, however the isotherms clearly demonstrate this characteristic. The pressure leads to the first harmonic, and the buoyancy, diffusion, and inertia forces produce the second harmonic.

scholarly journals Thermal boundary layer structure in convection with and without rotation

2020 ◽  
Vol 5 (11) ◽  
Author(s):  
Robert S. Long ◽  
Jon E. Mound ◽  
Christopher J. Davies ◽  
Steven M. Tobias
Keyword(s):  
Boundary Layer ◽  
Thermal Boundary Layer ◽  
Layer Structure ◽  
Boundary Layer Structure
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