scholarly journals Thermal boundary layer near roughnesses in turbulent Rayleigh-Bénard convection: Flow structure and multistability

2014 ◽  
Vol 26 (1) ◽  
pp. 015112 ◽  
Author(s):  
J. Salort ◽  
O. Liot ◽  
E. Rusaouen ◽  
F. Seychelles ◽  
J.-C. Tisserand ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Flow Structure ◽  
Thermal Boundary Layer ◽  
Convection Flow ◽  
Bénard Convection ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

scholarly journals Thermal boundary layer profiles in turbulent Rayleigh-Bénard convection in a cylindrical sample

2012 ◽  
Vol 85 (2) ◽  
Author(s):  
Richard J. A. M. Stevens ◽  
Quan Zhou ◽  
Siegfried Grossmann ◽  
Roberto Verzicco ◽  
Ke-Qing Xia ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Thermal Boundary Layer ◽  
Cylindrical Sample ◽  
Bénard Convection ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

scholarly journals Heat transfer in rotating Rayleigh–Bénard convection with rough plates

2017 ◽  
Vol 830 ◽  
Author(s):  
Pranav Joshi ◽  
Hadi Rajaei ◽  
Rudie P. J. Kunnen ◽  
Herman J. H. Clercx
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Ekman Layer ◽  
Ekman Pumping ◽  
Ekman Boundary Layer ◽  
Bénard Convection ◽  
Roughness Elements ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

This experimental study focuses on the effect of horizontal boundaries with pyramid-shaped roughness elements on the heat transfer in rotating Rayleigh–Bénard convection. It is shown that the Ekman pumping mechanism, which is responsible for the heat transfer enhancement under rotation in the case of smooth top and bottom surfaces, is unaffected by the roughness as long as the Ekman layer thickness $\unicode[STIX]{x1D6FF}_{E}$ is significantly larger than the roughness height $k$. As the rotation rate increases, and thus $\unicode[STIX]{x1D6FF}_{E}$ decreases, the roughness elements penetrate the radially inward flow in the interior of the Ekman boundary layer that feeds the columnar Ekman vortices. This perturbation generates additional thermal disturbances which are found to increase the heat transfer efficiency even further. However, when $\unicode[STIX]{x1D6FF}_{E}\approx k$, the Ekman boundary layer is strongly perturbed by the roughness elements and the Ekman pumping mechanism is suppressed. The results suggest that the Ekman pumping is re-established for $\unicode[STIX]{x1D6FF}_{E}\ll k$ as the faces of the pyramidal roughness elements then act locally as a sloping boundary on which an Ekman layer can be formed.

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