Thermo-Solutal Buoyancy Effect on Heat and Mass Transfer in a Backward-Facing Step Channel Under the Influence of Different Shapes of Nanoparticles

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Ratnadeep Nath ◽  
Murugesan Krishnan
Keyword(s):  
Mass Transfer ◽  
Mixed Convection ◽  
Heat And Mass Transfer ◽  
Alumina Nanoparticles ◽  
Buoyancy Effect ◽  
Backward Facing Step ◽  
Maximum Decrease ◽  
Vorticity Equations ◽  
Different Shapes ◽  
Double Diffusive

Abstract Double-diffusive mixed convection in a backward-facing step (BFS) channel for different shapes of nanoparticles is analyzed using velocity–vorticity equations. The effect of four shapes of alumina nanoparticles at volume fractions χ of 1–5% on heat and mass transfer are studied for buoyancy ratios, N from −3 to 3 at Re = 200, Ri = 0.1, and Pr = 6.2. As χ increases, the Nuav decreases for all shapes at N = −3; however, it increases with an increase in N from 1 to 3. At N = 3, the Nu increases by 29% for blades shape, whereas a 28% decrease was noticed for platelets shape. An increase in χ of nanoparticles results in a decrease of Shav for N = 1–3, with a maximum decrease of 57% being observed at N = −3 for cylinders shape. The τav at the bottom wall continues to increase up to a maximum of 400% for platelets shape for N = 3.

Numerical Three-Dimensional Double Diffusion Poiseuille-Rayleigh-Benard Flows in Rectangular Channels

2009 ◽  
Vol 283-286 ◽  
pp. 297-302 ◽  
Author(s):  
Omar Rahli ◽  
K. Bouhadef ◽  
Rachid Bennacer ◽  
Djamel Eddine Ameziani
Keyword(s):  
Mass Transfer ◽  
Mixed Convection ◽  
Heat And Mass Transfer ◽  
Three Dimensional ◽  
Double Diffusion ◽  
Flow Regimes ◽  
Dimensionless Parameters ◽  
Rectangular Channels ◽  
Rayleigh Benard ◽  
Double Diffusive

The contribution of this work is to characterize the travelling wave’s appearance and to generalize the behavior of Poiseuille-Rayleigh-Benard (PRB) systems for a broad range of dimensionless parameters, which control the double diffusive mixed convection. The numerical results consist to analyzing the flow regimes of the steady longitudinal thermoconvectives rolls for the case of purely thermal mixed convection and for both thermal and mass diffusion. The passage from an opposed volume forces to cooperating one at fixed Rayleigh (Ra), Reynolds (Re) and Lewis (Le) numbers, affects considerably the birth and the development of the longitudinal rolls R//. The distribution of the heat and mass transfer, presented by the average Nusselt and Sherwood numbers, is also examined.

Soret and Dufour effects on double diffusive mixed convection of Newtonian and shear-thinning fluids in a two sided lid-driven cavity

2016 ◽  
Vol 33 (7) ◽  
pp. 2117-2148
Author(s):  
Gholamreza Kefayati
Keyword(s):  
Mass Transfer ◽  
Mixed Convection ◽  
Heat And Mass Transfer ◽  
Power Law ◽  
Shear Thinning ◽  
Soret And Dufour Effects ◽  
Content Type ◽  
Driven Cavity ◽  
Power Law Index ◽  
Double Diffusive

Purpose The thermal-diffusion (Soret) and the diffusion-thermo (Dufour) effects play a crucial role in double diffusive mixed convection in a lid-driven cavity; but they have not been studied properly by researchers. The purpose of this paper is to investigate effects of Soret and Dufour parameters on double diffusive laminar mixed convection of shear-thinning and Newtonian fluids in a two-sided lid-driven cavity. Design/methodology/approach Finite Difference Lattice Boltzmann method (FDLBM) has been applied to solve the complex problem. This study has been conducted for the certain pertinent parameters of Richardson number (Ri=0.00062-1), power-law index (n=0.2-1), Soret parameter (Sr=−5-5) as Dufour number effects have been investigated from Dr=−5 to 5 at Buoyancy ratio of N=1 and Lewis number of Le=5. Findings Results indicate that the augmentation of Richardson number causes heat and mass transfer to decrease. The fall of the power-law index declines heat and mass transfer at Ri=0.00062 and 0.01 in various Dufour and Soret parameters. At Ri=1, the heat and mass transfer rise with the increment of power-law index for Dr=0 and Sr=0. The least effect of power-law index on heat and mass transfer among the studied Richardson numbers was observed at Ri=1. The positive Dufour numbers augment the heat transfer gradually as the positive Soret numbers enhance the mass transfer. The Dr=−5 and Sr=−5 provokes the negative average Nusselt and Sherwood numbers, respectively, to be generated. The least magnitude of the average Nusselt and Sherwood numbers were obtained at Dr=−1 and Sr=−1, respectively. Originality/value Soret and Dufour effects in double diffusive mixed convection has not been studied in a lid-driven cavity. In addition. this study has been conducted also for shear-thinning fluids.

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