Darcy-Forchheimer Flow of Magnetized Bioconvective Williamson Nanofluid with Variable Thermal Conductivity

AbstractThe present investigation deals with the steady three-dimensional flow and heat transfer of nanofluids due to stretching sheet in the presence of magnetic field and heat source. Three types of water based nanoparticles namely, copper (Cu), aluminium oxide (Al2O3), and titanium dioxide (TiO2) are considered in this study. The temperature dependent variable thermal conductivity and thermal radiation has been introduced in the energy equation. Using suitable similarity transformations the dimensional non-linear expressions are converted into dimensionless system and are then solved numerically by Runge-Kutta-Fehlberg scheme along with well-known shooting technique. The impact of various flow parameters on axial and transverse velocities, temperature, surface frictional coefficients and rate of heat transfer coefficients are visualized both in qualitative and quantitative manners in the vicinity of stretching sheet. The results reviled that the temperature and velocity of the fluid rise with increasing values of variable thermal conductivity parameter. Also, the temperature and normal velocity of the fluid in case of Cu-water nanoparticles is more than that of Al2O3- water nanofluid. On the other hand, the axial velocity of the fluid in case of Al2O3- water nanofluid is more than that of TiO2nanoparticles. In addition, the current outcomes are matched with the previously published consequences and initiate to be a good contract as a limiting sense.

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Effect of magnetized variable thermal conductivity on flow and heat transfer characteristics of unsteady Williamson fluid

Nonlinear Engineering ◽

10.1515/nleng-2020-0020 ◽

2020 ◽

Vol 9 (1) ◽

pp. 338-351

Author(s):

Usha Shankar ◽

N. B. Naduvinamani ◽

Hussain Basha

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Fluid Flow ◽

Velocity Profile ◽

Variable Thermal Conductivity ◽

Flow Index ◽

Williamson Fluid ◽

Flow Equations ◽

Velocity Parameter ◽

Squeezed Flow

AbstractA two-dimensional mathematical model of magnetized unsteady incompressible Williamson fluid flow over a sensor surface with variable thermal conductivity and exterior squeezing with viscous dissipation effect is investigated, numerically. Present flow model is developed based on the considered flow geometry. Effect of Lorentz forces on flow behaviour is described in terms of magnetic field and which is accounted in momentum equation. Influence of variable thermal conductivity on heat transfer is considered in the energy equation. Present investigated problem gives the highly complicated nonlinear, unsteady governing flow equations and which are coupled in nature. Owing to the failure of analytical/direct techniques, the considered physical problem is solved by using Runge-Kutta scheme (RK-4) via similarity transformations approach. Graphs and tables are presented to describe the physical behaviour of various control parameters on flow phenomenon. Temperature boundary layer thickens for the amplifying value of Weissenberg parameter and permeable velocity parameter. Velocity profile decreased for the increasing squeezed flow index and permeable velocity parameter. Increasing magnetic number increases the velocity profile. Magnifying squeezed flow index magnifies the magnitude of Nusselt number. Also, RK-4 efficiently solves the highly complicated nonlinear complex equations that are arising in the fluid flow problems. The present results in this article are significantly matching with the published results in the literature.

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Effects of variable thermal conductivity and electrical conductivity on flow of williamson nanofluid between two parallel disks

Modern Physics Letters B ◽

10.1142/s0217984921505266 ◽

2021 ◽

Author(s):

Mazmul Hussain ◽

Nargis Khan

Keyword(s):

Thermal Conductivity ◽

Differential Equations ◽

Electric Conductivity ◽

Variable Temperature ◽

Lewis Number ◽

Variable Thermal Conductivity ◽

Industrial Applications ◽

Weissenberg Number ◽

Modeling And Analysis ◽

Variable Nature

The variable nature of the thermal conductivity of nanofluid with respect to temperature plays an important role in many engineering and industrial applications including solar collectors and thermoelectricity. Thus, the foremost motivation of this article is to investigate the effects of thermal conductivity and electric conductivity due to variable temperature on the flow of Williamson nanofluid. The flow is considered between two stretchable rotating disks. The mathematical modeling and analysis have been made in the presence of magnetohydrodynamic and thermal radiation. The governing differential equations of the problem are transformed into non-dimensional differential equations by using similarity transformations. The transformed differential equations are thus solved by a finite difference method. The behaviors of velocity, temperature and concentration profiles due to various parameters are discussed. For magnetic parameter, the radial and tangential velocities have showed decreasing behavior, while converse behavior is observed for axial velocity. The temperature profile shows increasing behavior due to an increase in the Weissenberg number, heat generation parameter and Eckert number, while it declines by increasing electric conductivity parameter. The nanoparticle concentration profile declines due to an increase in the Lewis number and Reynolds number.

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Thermal radiation effects on MHD flow of a micropolar fluid over a stretching surface with variable thermal conductivity

Physica A Statistical Mechanics and its Applications ◽

10.1016/j.physa.2006.09.010 ◽

2007 ◽

Vol 375 (2) ◽

pp. 401-410 ◽

Cited By ~ 75

Author(s):

Mostafa A.A. Mahmoud

Keyword(s):

Thermal Conductivity ◽

Thermal Radiation ◽

Micropolar Fluid ◽

Radiation Effects ◽

Mhd Flow ◽

Variable Thermal Conductivity ◽

Stretching Surface

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The Impact of Variable Thermal Conductivity of Insulation Materials on the Building Energy Performance in Hot Climate

E3S Web of Conferences ◽

10.1051/e3sconf/201910302001 ◽

2019 ◽

Vol 103 ◽

pp. 02001 ◽

Cited By ~ 3

Author(s):

Maatouk Khoukhi ◽

Ahmed Hassan ◽

Shaimaa Abdelbaqi

Keyword(s):

Thermal Conductivity ◽

Energy Performance ◽

Variable Thermal Conductivity ◽

Transfer Model ◽

Ambient Conditions ◽

K Value ◽

Hot Climate ◽

Building Wall ◽

Wall Assembly ◽

The Impact

This paper illustrates the impact of embedding an insulation layer of variable thermal conductivity in a typical building wall on the cooling effect and energy performance. The evaluation was performed by applying a conjugate heat transfer model, which was tested in extremely hot conditions of Al Ain (UAE). The thermal performance of a building incorporating insulation layers of variable thermal conductivity (k-value) was compared to a non-variable thermal conductivity system by quantifying the additional heat transferred due to the k-relationship with time. The results show that, when the k-value is a function of operating temperature, its effects on the temperature profile through the wall assembly during daytime is significant compared with that obtained when a constant k-value for the polystyrene (EPS) insulation is adopted. A similar trend in the evolution of temperatures during the day and across the wall section was observed when EPS material with different moisture content was evaluated. For the polyurethane insulation, the inner surface temperature reached 44 °C when constant k-value was adopted, increasing to 48.5 °C when the k-value was allowed to vary under the same ambient conditions.

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