Effects of internal heat source and soret on the onset of Rayleigh–Bénard convection in a nanofluid layer

2018 ◽  
Author(s):  
Izzati Khalidah Khalid ◽  
Nor Fadzillah Mohd Mokhtar ◽  
Zailan Siri ◽  
Zarina Bibi Ibrahim ◽  
Siti Salwa Abd Gani
Keyword(s):  
Heat Source ◽  
Internal Heat ◽  
Internal Heat Source ◽  
Bénard Convection ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

scholarly journals Numerical simulation of helical-vortex effects in Rayleigh-Bénard convection

2006 ◽  
Vol 13 (2) ◽  
pp. 205-222 ◽  
Author(s):  
G. V. Levina ◽  
I. A. Burylov
Keyword(s):  
Large Scale ◽  
Internal Heat ◽  
Main Idea ◽  
Numerical Approach ◽  
Small Scale ◽  
Forcing Function ◽  
Bénard Convection ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

Abstract. A numerical approach is substantiated for searching for the large-scale alpha-like instability in thermoconvective turbulence. The main idea of the search strategy is the application of a forcing function which can have a physical interpretation. The forcing simulates the influence of small-scale helical turbulence generated in a rotating fluid with internal heat sources and is applied to naturally induced fully developed convective flows. The strategy is tested using the Rayleigh-Bénard convection in an extended horizontal layer of incompressible fluid heated from below. The most important finding is an enlargement of the typical horizontal scale of the forming helical convective structures accompanied by a cells merging, an essential increase in the kinetic energy of flows and intensification of heat transfer. The results of modeling allow explaining how the helical feedback can work providing the non-zero mean helicity generation and the mutual intensification of horizontal and vertical circulation, and demonstrate how the energy of the additional helical source can be effectively converted into the energy of intensive large-scale vortex flow.

scholarly journals Rayleigh-Benard Convection in Nanofluids Layer saturated in a Rotating Anisotropic Porous Medium with Feedback Control and Internal Heat Source

CFD Letters ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1-20
Author(s):  
Izzati Khalidah Khalid ◽  
Nor Fadzillah Mohd Mokhtar ◽  
Zarina Bibi Ibrahim
Keyword(s):  
Feedback Control ◽  
Heat Source ◽  
Porous Layer ◽  
Control Strategy ◽  
Anisotropy Parameter ◽  
Internal Heat ◽  
Internal Heat Source ◽  
Free Boundaries ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

Control strategy on Rayleigh-Benard convection in rotating nanofluids saturated in anisotropic porous layer heated from below is studied in the presence of uniformly internal heat source for rigid-rigid, free-free, and lower-rigid and upper-free boundaries. Feedback control strategy with an array of sensors situated at the top plate and actuators located at the bottom plate of the nanofluids layer are considered in this study. Linear stability analysis based on normal mode technique has been performed, the eigenvalue problem is obtained numerically by implementing the Galerkin method and computed by using Maple software. Model employed for the nanofluids includes the mechanisms of Brownian motion and thermophoresis. The problem of the onset of convective rolls instabilities in a horizontal porous layer with isothermal boundaries at unequal temperatures known as Horton-Roger-Lapwood model based on the Darcy model for the fluids flow is used. The influences of internal heat source’s strength, modified diffusivity ratio, nanoparticles concentration Darcy-Rayleigh number and nanofluids Lewis number are found to advance the onset of convection, meanwhile the mechanical anisotropy parameter, thermal anisotropy parameter, porosity, rotation, and controller effects are to slow down the process of convective instability. No visible observation on the modified particle density increment and rigid-rigid boundaries are the most stable system compared to free-free and rigid-free boundaries.

scholarly journals Uniform Solution on the Combined Effect of Magnetic Field and Internal Heat Generation on Rayleigh–Bénard Convection in Micropolar Fluid

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
I. K. Khalid ◽  
N. F. M. Mokhtar ◽  
N. M. Arifin
Keyword(s):  
Magnetic Field ◽  
Heat Generation ◽  
Micropolar Fluid ◽  
Internal Heat ◽  
Internal Heat Generation ◽  
Combined Effect ◽  
Bénard Convection ◽  
Benard Convection ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

Combined effect of magnetic field and internal heat generation on the onset of Rayleigh–Bénard convection in a horizontal micropolar fluid layer is studied. The bounding surfaces of the liquids are considered to be rigid-free, rigid-rigid, and free-free with combination isothermal on the spin-vanishing boundaries. A linear stability analysis is used and the Galerkin method is employed to find the critical stability parameters numerically. The influence of various parameters on the onset of convection has been analyzed. It is shown that the presence of magnetic field always has a stability effect on the Rayleigh–Bénard convection in micropolar fluid.

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