Numerical study of unsteady, thermally-stratified shear flows in superposed porous and pure-fluid domains

Antoniadis, Panagiotis; Papalexandris, Miltiadis

doi:10.1016/j.ijheatmasstransfer.2016.01.056

Cited by 14 publications

(3 citation statements)

References 39 publications

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“…where ñ is the unit vector normal to the interface. For a discussion on the appropriateness and applicability of this condition, the reader is referred to the papers by and Antoniadis & Papalexandris (2016).…”

Section: Governing Equationsmentioning

confidence: 99%

Turbulent thermal convection in mixed porous–pure fluid domains

Hamtiaux

Papalexandris

2023

J. Fluid Mech.

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In this paper, we report on a direct numerical simulation (DNS) study of turbulent thermal convection in mixed porous–pure fluid domains. The computational domain consists of a cavity that contains a porous medium placed right above the bottom wall. The solid matrix is internally heated which, in turn, induces the convective motions of the fluid. The Rayleigh number of the flow in the pure fluid region above the porous medium is of the order of $10^7$ . In our study, we consider cases of different sizes of the porous medium, as well as cases with both uniform and non-uniform heat loading of the solid matrix. For each case, we analyse the convective structures in both the porous and the pure fluid domains and investigate the effect of the porous medium on the emerging flow patterns above it. Results for the flow statistics, as well as for the Nusselt number and each of its components, are also presented herein. Further, we make comparisons of the flow properties in this pure fluid region with those in Rayleigh–Bénard convection. Our simulations predict that, depending on the area coverage, the large-scale circulation above the porous medium can be in a single-roll, dual-roll or intermediate state. Also, when the area coverage increases, the temperatures inside it increase due to reduced fluid circulation. Accordingly, when the area coverage increases, then the Nusselt number becomes smaller whereas the Rayleigh number is increased.

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Section: Governing Equationsmentioning

confidence: 99%

Turbulent thermal convection in mixed porous–pure fluid domains

Hamtiaux

Papalexandris

2023

J. Fluid Mech.

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“…Also p ′ stands for the piezometric pressure [16,17], p ′ = p + ρRiy with p being the sum of the dynamic and bulk-viscous pressures [18]. In (2), y is the spatial coordinate in the vertical direction and opposite to gravity, and S is twice the deviatoric part of the strain-rate tensor, S = (∇u + ∇u ⊤ ) − 2 3 (∇ • u)I, with I being the identity matrix.…”

Section: Governing Equationsmentioning

confidence: 99%

Multiple Steady States in Laminar Rayleigh–Bénard Convection of Air

Carlier,

Papalexandris

2023

Fluids

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In this article, we report on numerical simulations of laminar Rayleigh–Bénard convection of air in cuboids. We provide numerical evidence of the existence of multiple steady states when the aspect ratio of the cuboid is sufficiently large. In our simulations, the Rayleigh number is fixed at Ra=1.7×104. The gas in the cube is initially at rest but subject to random small-amplitude velocity perturbations and an adverse temperature gradient. When the flow domain is a cube, i.e., the aspect ratio is equal to unity, there is only one steady state. This state is characterized by the development of a single convective roll and by a symmetric normalized temperature profile with respect to the mid-height. On the contrary, when the aspect ratio is equal to 2, there are five different steady states. Only one of them exhibits a symmetric temperature profile and flow structure. The other four steady states are characterized by two-roll configurations and asymmetric temperature profiles.

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“…Þ and utilizing similarity transformations given in equations (12) to (14), equations (2) and (3) along with stated boundary conditions given in equation (4) reduce to the following system of equations and corresponding boundary conditions…”

Section: Solution Proceduresmentioning

confidence: 99%

Impact of magnetic dipole on a thermally stratified ferrofluid past a stretchable surface

Muhammad

Nadeem

Mustafa

2018

Proceedings of the Institution of Mechanical Engineers, Part E:

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This article focuses on the characteristics of a magnetic dipole in a viscous ferrofluid induced by linear stretched surface. The analysis is disclosed by thermally stratified phenomenon and stagnation point. It is also noticed that the impact of magneto-thermomechanical coupling is inspected numerically via BVPh2–midpoint method. It is perceived that thermal stratification has significant characteristics in controlling the rate of heat transfer inside the boundary layer. It is also noticed that the impact of magneto-thermomechanical interaction decelerates the motion of the fluid as compared to hydrodynamic case, thereby enhancing the skin friction and decreasing the heat transfer rate at surface. It is depicted that the ferrohydrodynamic parameter results in the reduction of axial velocity thereby enhances the temperature profile.

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Numerical study of unsteady, thermally-stratified shear flows in superposed porous and pure-fluid domains

Cited by 14 publications

References 39 publications

Turbulent thermal convection in mixed porous–pure fluid domains

Turbulent thermal convection in mixed porous–pure fluid domains

Multiple Steady States in Laminar Rayleigh–Bénard Convection of Air

Impact of magnetic dipole on a thermally stratified ferrofluid past a stretchable surface

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