Flow and thermal analysis of Jeffrey nanofluid in a microchannel: Buongiorno's Model

2021 ◽  
pp. 095440892110501
Author(s):  
D.O. Soumya ◽  
B.J. Gireesha ◽  
P. Venkatesh ◽  
Abdulmohsen Alsaiari
Keyword(s):  
Thermal Conductivity ◽  
Brownian Motion ◽  
Thermal Energy ◽  
Energy Concentration ◽  
Physical Parameters ◽  
Temperature Dependent ◽  
Jeffrey Nanofluid ◽  
The Impact ◽  
Temperature Dependent Thermal Conductivity ◽  
Irreversibility Ratio

The present consideration explores the thermal energy and mass transfer process in conducting Jeffrey nanofluid flows through a microchannel. The slip boundary conditions, Brownian motion and temperature-dependent thermal conductivity were considered. The dimensionless governing models have been solved to the best possible investigative solutions using the Runge-Kutta-Fehlberg 4 −5th order numerical procedure. The impact of physical parameters on the momentum, energy, concentration, irreversibility and irreversibility ratio was revealed graphically in detail. It is concluded that the resultant momentum profile is augmented with the relaxation and retardation times parameter all over the flow region. The temperature-dependent thermal conductivity contributes to the resulting thermal energy of the flow system ever-growing to high. The concentration profile was diminutions through growing in the Brownian motion parameter. The irreversibility and irreversibility ratio were obtained mathematically and explained concerning the notable parameters. The magnetic parameter was to diminish the irreversibility rate, but it was augmented by increasing the parameter for the relaxation and retardation times ratio. Effect of thermal radiation, variable thermal conductivity, pressure gradient, buoyancy force and thermophoresis on the Jeffery nanofluid in a microchannel by the Buongiorno model have been inspected for the first time. The effects of this works are innovative and original.

Stagnant lid convection with temperature-dependent thermal conductivity and the thermal evolution of icy worlds

2020 ◽  
Vol 224 (3) ◽  
pp. 1870-1889
Author(s):  
Frédéric Deschamps
Keyword(s):  
Thermal Conductivity ◽  
Thermal Evolution ◽  
Heat Fluxes ◽  
The Body ◽  
Temperature Dependent ◽  
Temperature Dependent Conductivity ◽  
Icy Bodies ◽  
Main Component ◽  
The Impact ◽  
Temperature Dependent Thermal Conductivity

SUMMARY Convection is an efficient process to release heat from planetary interiors, but its efficiency depends on the detailed properties of planetary mantles and materials. A property whose impact has not yet been studied extensively is the temperature dependence of thermal conductivity. Because thermal conductivity controls heat fluxes, its variations with temperature may alter heat transfer. Here, I assess qualitatively and quantitatively the influence of temperature-dependent thermal conductivity on stagnant lid convection. Assuming that thermal conductivity varies as the inverse of temperature $(k \propto 1/T)$, which is the case for ice Ih, the main component of outer shells of solar System large icy bodies, I performed numerical simulations of convection in 3-D-Cartesian geometry with top-to-bottom viscosity and conductivity ratios in the ranges 105 ≤ Δη ≤ 108 and 1 ≤ Rk ≤ 10, respectively. These simulations indicate that with increasing Rk, and for given values of the Rayleigh number and Δη, heat flux is reduced by a factor Rk0.82, while the stagnant lid is thickening. These results have implications for the structures and thermal evolutions of large icy bodies, the impact of temperature-dependent conductivity being more important with decreasing surface temperature, Tsurf. The heat fluxes and thermal evolutions obtained with temperature-dependent conductivity are comparable to those obtained with constant conductivity, provided that the conductivity is fixed to its value at the bottom or in the interior of the ice shell, that is, around 2.0–3.0 W m−1 K−1, depending on the body. By contrast, temperature-dependent conductivity leads to thicker stagnant lids, by about a factor 1.6–1.8 at Pluto (Tsurf = 40 K) and a factor 1.2–1.4 at Europa (Tsurf = 100 K), and smaller interior temperatures. Overall, temperature-dependent thermal conductivity therefore provides more accurate descriptions of the thermal evolutions of icy bodies.

Forced Convection of MHD Radiative Jeffrey Nanofluid Over a Moving Plate

2021 ◽  
Vol 87 (1) ◽  
pp. 12-19
Author(s):  
Syazwani Mohd Zokri ◽  
Nur Syamilah Arifin ◽  
Abdul Rahman Mohd Kasim ◽  
Norhaslinda Zullpakkal ◽  
Mohd Zuki Salleh
Keyword(s):  
Brownian Motion ◽  
Numerical Solutions ◽  
Graphical Representation ◽  
Physical Parameters ◽  
Concentration Profiles ◽  
Moving Plate ◽  
Parameter Ratio ◽  
Nanoparticles Concentration ◽  
Jeffrey Nanofluid ◽  
The Impact

Convectively heated Jeffrey nanofluid flow in the presence of magnetic field and thermal radiation is investigated from a moving plate. Parameter of Brownian motion from Boungiorno model is the imperative mechanism that contributes to the heat transfer enhancement. Governing equations, consisting of the continuity, momentum, energy and nanoparticle concentrations equations are transformed into dimensionless form by means of the appropriate similarity transformation variables. Numerical results via Runge-Kutta Fehlberg Fourth-Fifth order (RKF45) method are specifically acquired on the impact of physical parameters such as Brownian motion, magnetic parameter, ratio of relaxation to retardation and radiation parameters over the temperature and nanoparticles concentration profiles. Comparison of the present results with existing published studies has validated the accuracy of the numerical solutions. Graphical representation of different magnetic parameters has caused the increment in both temperature and nanoparticles concentration profiles. On the other hand, enhancement of Brownian motion has intensified the temperature but declined the nanoparticles concentration.

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