Role of distributed/discrete solar heaters during natural convection in the square and triangular cavities: CFD and heatline simulations

Solar Energy ◽  
2016 ◽  
Vol 135 ◽  
pp. 130-153 ◽  
Author(s):  
Debayan Das ◽  
Tanmay Basak
Keyword(s):  
Natural Convection

THE ROLE OF NATURAL CONVECTION ON DROPLET EVAPORATION

2019 ◽  
Author(s):  
Abgail Paula Pinheiro ◽  
João Marcelo Vedovoto
Keyword(s):  
Natural Convection ◽  
Droplet Evaporation

Natural convection in a corrugated slot

2017 ◽  
Vol 815 ◽  
pp. 537-569 ◽  
Author(s):  
Arman Abtahi ◽  
J. M. Floryan
Keyword(s):  
Natural Convection ◽  
Heat Flow ◽  
Convective Heat ◽  
Phase Difference ◽  
Conductive Heat ◽  
Heat Transfer Augmentation ◽  
Conductive Heat Flow ◽  
Secondary Motion ◽  
Prandtl Numbers

Analysis of natural convection in a horizontal slot formed by two corrugated isothermal plates has been carried out. The analysis is limited to subcritical Rayleigh numbers$Ra$where no secondary motion takes place in the absence of corrugations. The corrugations have a sinusoidal form characterized by the wavenumber, the upper and lower amplitudes and the phase difference. The most intense convection occurs for corrugation wavelengths comparable to the slot height; it increases proportionally to$Ra$and proportionally to the corrugation height. Placement of corrugations on both plates may either significantly increase or decrease the convection depending on the phase difference between the upper and lower corrugations, with the strongest convection found for corrugations being in phase, i.e. a ‘wavy’ slot, and the weakest for corrugations being out of phase, i.e. a ‘converging–diverging’ slot. It is shown that the shear forces would always contribute to the corrugation build-up if erosion was allowed, while the role of pressure forces depends on the location of the corrugations as well as on the corrugation height and wavenumber, and the Rayleigh number. Placing corrugations on both plates results in the formation of a moment which attempts to change the relative position of the plates. There are two limiting positions, i.e. the ‘wavy’ slot and the ‘converging–diverging’ slot, with the latter being unstable. The system would end up in the ‘wavy’ slot configuration if relative movement of the two plates was allowed. The presence of corrugations affects the conductive heat flow and creates a convective heat flow. The conductive heat flow increases with the corrugation height as well as with the corrugation wavenumber; it is largest for short-wavelength corrugations. The convective heat flow is relevant only for wavenumbers of$O(1)$, it increases proportionally to$Ra^{3}$and proportionally to the second power of the corrugation height. Convection is qualitatively similar for all Prandtl numbers$Pr$, with its intensity increasing for smaller$Pr$and with the heat transfer augmentation increasing for larger$Pr$.

scholarly journals Role of thermal diffusion on double-diffusive natural convection in a vertical annular porous medium

2015 ◽  
Vol 6 (2) ◽  
pp. 629-637 ◽  
Author(s):  
Basant Kumar Jha ◽  
Sylvester Bakut Joseph ◽  
Abiodun Olusegun Ajibade
Keyword(s):  
Porous Medium ◽  
Natural Convection ◽  
Thermal Diffusion ◽  
Double Diffusive
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