The Effect of Local Thermal Nonequilibrium on the Onset of Convection in a Nanofluid

The onset of convection in a horizontal layer of a nanofluid is studied analytically. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis, and allows for local thermal nonequilibrium (LTNE) between the particle and fluid phases. The analysis reveals that in some circumstances, the effect of LTNE can be significant, but for a typical dilute nanofluid (with large Lewis number and with small particle-to-fluid heat capacity ratio), the effect is small.

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The Onset of Convection in an Internally Heated Nanofluid Layer

Journal of Heat Transfer ◽

10.1115/1.4025048 ◽

2013 ◽

Vol 136 (1) ◽

Cited By ~ 11

Author(s):

D. A. Nield ◽

A. V. Kuznetsov

Keyword(s):

Brownian Motion ◽

Boundary Conditions ◽

Microwave Heating ◽

Chemical Reaction ◽

Vertical Gradient ◽

Horizontal Layer ◽

Internal Heating ◽

Onset Of Convection ◽

Brownian Motion And Thermophoresis ◽

Heating From Below

We analytically studied the onset of convection, induced by internal heating, such as that produced by microwave heating or chemical reaction, in a horizontal layer of a nanofluid subject to Brownian motion and thermophoresis. This is a fundamentally different situation from traditionally studied heating from below. Convection, when it occurs, is now concentrated in the portion of the layer where the upward vertical gradient is negative, which is the upper portion of the layer. The situation of internal heating also allows employing more realistic boundary conditions than those hitherto used.

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A Revised Model for Magneto Convection in Binary Nanofluids

International Journal of Mathematical Engineering and Management Sciences ◽

10.33889//ijmems.2019.4.1-012 ◽

2019 ◽

Vol 4 (1) ◽

pp. 131-138 ◽

Cited By ~ 2

Author(s):

Jyoti Sharma ◽

Urvashi Gupta ◽

Shushant Shukla

Keyword(s):

Magnetic Field ◽

Brownian Motion ◽

Normal Mode ◽

Scale Effects ◽

Onset Of Convection ◽

Nano Scale ◽

Brownian Motion And Thermophoresis ◽

Mode Technique ◽

Double Diffusive

The paper presents double-diffusive nanofluid convection under magnetic field using more realistic revised model in which boundaries are assumed to have zero nanoparticle flux. The nanofluid layer includes the nano scale effects (Brownian motion and thermophoresis) and solutal effects (Dufour and Soret). Impact of different parameters is analyzed using normal mode technique and interpreted graphically with the help of the software Mathematica. Complex expressions for oscillatory motions are solved using approximations to confirm their non-existence and onset of convection is established as stationary. Binary nanofluids are found to be much less stable than regular fluids. Higher conductivity of metallic nanofluids makes them less stable as compared to non-metallic nanofluids.

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Rayleigh-Bénard convection in an elastico-viscous Walters’ (model B’) nanofluid layer

Bulletin of the Polish Academy of Sciences Technical Sciences ◽

10.1515/bpasts-2015-0028 ◽

2015 ◽

Vol 63 (1) ◽

pp. 235-244 ◽

Cited By ~ 1

Author(s):

G.C. Rana ◽

R. Chand

Keyword(s):

Fluid Model ◽

Normal Mode Analysis ◽

Sufficient Conditions ◽

Lewis Number ◽

Horizontal Layer ◽

Linear Stability Theory ◽

Mode Analysis ◽

Physical Parameters ◽

Onset Of Convection ◽

The Stability

Abstract In this study, the onset of convection in an elastico-viscous Walters’ (model B’) nanofluid horizontal layer heated from below is considered. The Walters’ (model B’) fluid model is employed to describe the rheological behavior of the nanofluid. By applying the linear stability theory and a normal mode analysis method, the dispersion relation has been derived. For the case of stationary convection, it is observed that the Walters’ (model B’) elastico-viscous nanofluid behaves like an ordinary Newtonian nanofluid. The effects of the various physical parameters of the system, namely, the concentration Rayleigh number, Prandtl number, capacity ratio, Lewis number and kinematics visco-elasticity coefficient on the stability of the system has been numerically investigated. In addition, sufficient conditions for the non-existence of oscillatory convection are also derived.

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EFFECTS OF LOCAL THERMAL NONEQUILIBRIUM ON THE ONSET OF CONVECTION IN A MAGNETIC NANOFLUID LAYER

Heat Transfer Research ◽

10.1615/heattransres.2020031119 ◽

2020 ◽

Vol 51 (7) ◽

pp. 689-705

Author(s):

Amit Mahajan ◽

Mahesh Kumar Sharma

Keyword(s):

Onset Of Convection ◽

Thermal Nonequilibrium ◽

Magnetic Nanofluid ◽

Local Thermal Nonequilibrium

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The onset of magnetic nanofluid convection because of selective absorption of radiation

JOURNAL OF MECHANICAL ENGINEERING AND SCIENCES ◽

10.15282/jmes.15.1.2021.25.0625 ◽

2021 ◽

Vol 15 (1) ◽

pp. 7918-7935

Author(s):

Amit Mahajan ◽

Mahesh Kumar Sharma

Keyword(s):

Pseudospectral Method ◽

Lewis Number ◽

Horizontal Layer ◽

Selective Absorption ◽

Onset Of Convection ◽

Magnetic Nanofluid ◽

Chebyshev Pseudospectral Method ◽

The Impact ◽

Chebyshev Pseudospectral ◽

Diffusivity Ratio

This article reports a linear stability analysis of the onset of convection stimulated by selective absorption of radiation in a horizontal layer of magnetic nanofluid (MNF) under the impact of an external magnetic field. The Chebyshev pseudospectral method is utilized to obtain the numerical solution for water-based magnetic nanofluids (MNFs). The confining boundaries of the magnetic nanofluid layer are considered to be rigid–rigid, rigid–free, and free–free. The results are derived for two different conditions, viz., when the system is heated from the below and when the system is heated from the above. It is observed that an increase in the value of the Langevin parameter , diffusivity ratio and a decrease in the value of nanofluid Lewis number , the parameter which represents the impact of selective absorption of radiation and modified diffusivity ratio delays the onset of MNF convection for both the two configurations. Moreover, as the value of concentration Rayleigh number increases, the convection commences easily when the system is heated from the below, whereas the onset of MNF convection gets delayed as the system is heated from the above.

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