Rayleigh–Bénard convection in Maxwell nanofluids layer saturated in a rotating porous medium with feedback control subjected to viscosity and thermal conductivity variations

2020 ◽  
Vol 10 (8) ◽  
pp. 3085-3095
Author(s):  
Izzati Khalidah Khalid ◽  
Nor Fadzillah Mohd Mokhtar ◽  
Zarina Bibi Ibrahim ◽  
Zailan Siri
Keyword(s):  
Thermal Conductivity ◽  
Porous Medium ◽  
Feedback Control ◽  
Bénard Convection ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

Effect of Sidewall Conductance on Nusselt Number for Rayleigh-Bénard Convection: A Semi-Analytical and Experimental Correction

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
U. Madanan ◽  
R. J. Goldstein
Keyword(s):  
Thermal Conductivity ◽  
Nusselt Number ◽  
Analytical Model ◽  
Thermal Conductance ◽  
Bénard Convection ◽  
Benard Convection ◽  
Extended Surfaces ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard ◽  
Good Agreement

Abstract The effect of sidewall conductance on Nusselt number for the Rayleigh-Bénard convection is examined by performing nearly identical sets of experiments with sidewalls made of three different materials. These experimental results are utilized to extrapolate and estimate the Nusselt number for an ideal zero-thermal-conductivity sidewall case, which is the case when the sidewalls are perfectly insulating. A semi-analytical model is proposed, based on the concept of extended surfaces, to compute the discrepancy in Nusselt number caused by the presence of finite thermal conductance of the sidewalls. The predictions obtained using this model are found to be in good agreement with the corresponding experimentally determined values.

scholarly journals Robust feedback control of Rayleigh–Bénard convection

2001 ◽  
Vol 437 ◽  
pp. 175-202 ◽  
Author(s):  
A. C. OR ◽  
L. CORTELEZZI ◽  
J. L. SPEYER
Keyword(s):  
Feedback Control ◽  
Critical Rayleigh Number ◽  
Linear Quadratic ◽  
Parameter Uncertainties ◽  
Sensor Model ◽  
Motion State ◽  
Bénard Convection ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

We investigate the application of linear-quadratic-Gaussian (LQG) feedback control, or, in modern terms, [Hscr ]2 control, to the stabilization of the no-motion state against the onset of Rayleigh–Bénard convection in an infinite layer of Boussinesq fluid. We use two sensing and actuating methods: the planar sensor model (Tang & Bau 1993, 1994), and the shadowgraph model (Howle 1997a). By extending the planar sensor model to the multi-sensor case, it is shown that a LQG controller is capable of stabilizing the no-motion state up to 14.5 times the critical Rayleigh number. We characterize the robustness of the controller with respect to parameter uncertainties, unmodelled dynamics. Results indicate that the LQG controller provides robust performances even at high Rayleigh numbers.

Küppers-Lortz instability in rotating Rayleigh-Bénard convection in a porous medium

Meccanica ◽  
2013 ◽  
Vol 48 (10) ◽  
pp. 2401-2414 ◽  
Author(s):  
Y. Rameshwar ◽  
Shakira Sultana ◽  
S. G. Tagare
Keyword(s):  
Porous Medium ◽  
Bénard Convection ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard
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