The effect of local thermal non-equilibrium on the onset of thermal instability for a metallic foam

Freitas, Rômulo Bessi; Brandão, Pedro Vayssière; Alves, Leonardo Santos de Brito; Celli, Michele; Barletta, Antonio

doi:10.1063/5.0083045

Cited by 8 publications

(2 citation statements)

References 28 publications

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“…This feature yields, for intense thermal loads, a Local Thermal Non-Equilibrium (LTNE) between the solid and the fluid phases [53]. Regarding the stability analysis of the horizontal flow in a saturated porous layer, the LTNE has a destabilizing effect on the onset of both convective and absolute instabilities, independently of the Péclet number associated with the horizontal flow rate and the aspect ratio [54]. This non-equilibrium can be investigated by employing a twotemperature model.…”

Section: Metal Foams and Local Thermal Non-equilibriummentioning

confidence: 99%

Heat Transfer and Thermal Energy Storage Enhancement by Foams and Nanoparticles

Andreozzi,

Asinari,

Barletta

et al. 2023

Energies

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The use of innovative methods for the design of heating, cooling, and heat storage devices has been mainly oriented in the last decade toward the use of nanofluids, metal foams coupled with working fluids, or phase change materials (PCMs). A network of nine Italian universities achieved significant results and innovative ideas on these topics by developing a collaborative project in the last four years, where different approaches and investigation techniques were synergically employed. They evaluated the quantitative extent of the enhancement in the heat transfer and thermal performance of a heat exchanger or thermal energy storage system with the combined use of nanofluids, metal foams, and PCMs. The different facets of this broad research program are surveyed in this article. Special focus is given to the comparison between the mesoscopic to macroscopic modeling of heat transfer in metal foams and nanofluids, as well as to the experimental data collected and processed in the development of the research.

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Section: Metal Foams and Local Thermal Non-equilibriummentioning

confidence: 99%

Heat Transfer and Thermal Energy Storage Enhancement by Foams and Nanoparticles

Andreozzi,

Asinari,

Barletta

et al. 2023

Energies

Self Cite

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“…The problem of thermal convection in porous media in LTNE has been widely studied over the last years, starting from [23,24], in which both a linear and nonlinear analysis is carried out. Many papers analysed the effect of LTNE on the onset of convection, coupled to rotation and/or anisotropy [25][26][27][28][29], magnetic field [30], vertical throughflow [31,32], and also in non-horizontal porous layer [33][34][35]. Interesting results are obtained once the assumption of LTNE is combined with the Cattaneo's law for heat conduction in the solid matrix, since in such a case convection by means of oscillatory motions can occur [36][37][38][39].…”

Section: Introductionmentioning

confidence: 99%

Natural convection in a fluid saturating an anisotropic porous medium in LTNE: effect of depth-dependent viscosity

Capone

Gianfrani

2022

Acta Mech

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Thermal convection in a fluid saturating an anisotropic porous medium in local thermal nonequilibrium (LTNE) is investigated, with specific attention to the effect of variable viscosity on the onset of convection. Many fluids show a remarkable dependence of viscosity on temperature that cannot be neglected. For this reason, we take into account a fluid whose viscosity decreases exponentially with depth, according to Straughan (Acta Mech. 61:59–72, 1986), Torrance and Turcotte (J. Fluid Mech. 47(1):113–125, 1971). The novelty of this paper is to highlight how variable viscosity coupled with the LTNE assumption affects the onset of convection. A numerical procedure shows the destabilising effect of depth-dependent viscosity. Moreover, it comes out that the LTNE hypothesis makes the influence of viscosity more intense. Linear instability analysis of the conduction solution is carried out by means of the Chebyshev-tau method coupled to the QZ algorithm, which provides the critical Rayleigh number for the onset of convection in a straightforward way. The energy method is employed in order to study the nonlinear stability. The optimal result of coincidence between the linear instability threshold and the global nonlinear stability threshold is obtained. The influence of anisotropic permeability and conductivity, weighted conductivity ratio, and interaction coefficient on the onset of convection is highlighted.

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Effect of Vadasz term on the onset of convection in a Darcy–Brinkman anisotropic rotating porous medium in LTNE

Capone

Gianfrani

2023

Continuum Mech. Thermodyn.

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In the present paper, the effect of the Vadasz inertia term on the onset of convective motions for a Darcy–Brinkman model is investigated. It is proved that this term leads to the possibility for oscillatory convection to occur. Hence, convection can occur via either oscillatory or steady motions. It is proved analytically that the onset of steady convection is not affected by the Vadasz term, while oscillatory convection is favoured by it. Moreover, conditions to rule out the occurrence of oscillatory convection are determined numerically. The influence of rotation, interaction coefficient and mechanical and thermal anisotropies on the onset of instability is investigated, both analytically and numerically.

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The effect of local thermal non-equilibrium on the onset of thermal instability for a metallic foam

Cited by 8 publications

References 28 publications

Heat Transfer and Thermal Energy Storage Enhancement by Foams and Nanoparticles

Heat Transfer and Thermal Energy Storage Enhancement by Foams and Nanoparticles

Natural convection in a fluid saturating an anisotropic porous medium in LTNE: effect of depth-dependent viscosity

Effect of Vadasz term on the onset of convection in a Darcy–Brinkman anisotropic rotating porous medium in LTNE

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