scholarly journals Natural convection of $$\mathrm {Al}_{2}\mathrm {O}_{3}$$-water nanofluid in a non-Darcian wavy porous cavity under the local thermal non-equilibrium condition

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ammar I. Alsabery ◽  
Tahar Tayebi ◽  
Ali J. Chamkha ◽  
Ishak Hashim
Keyword(s):  
Equilibrium Condition ◽  
Convective Motion ◽  
Darcy Number ◽  
Element Discretization ◽  
Heated Part ◽  
Nanoparticles Concentration ◽  
Vertical Walls ◽  
Wavy Cavity ◽  
Heater Length ◽  
Non Equilibrium

Abstract This study investigates thermal natural convective heat transfer in a nanofluid filled-non-Darcian porous and wavy-walled domain under the local thermal non-equilibrium condition. The considered cavity has corrugated and cold vertical walls and insulated horizontal walls except the heated part positioned at the bottom wall. The transport equations in their non-dimensional model are numerically solved based on the Galerkin finite-element discretization technique. The dimensionless governing parameters of the present work are the nanoparticle in volume concentration, the Darcy number, number of undulations, modified heat conductivity ratio, dimensionless heated part length, and location. Comparisons with other published theoretical and experimental results show good agreement with the present outcomes. The findings indicate that the heater length, its position, and the waves number on the side vertical walls as well as the nanoparticles concentration can be the control parameters for free convective motion and heat transport within the wavy cavity.

scholarly journals Temperature fields in a channel partially filled with a porous material under local thermal non-equilibrium condition – An exact solution

2014 ◽  
Vol 228 (15) ◽  
pp. 2778-2789 ◽  
Author(s):  
Nader Karimi ◽  
Yasser Mahmoudi ◽  
Kiumars Mazaheri
Keyword(s):  
Porous Material ◽  
Fluid Transport ◽  
Darcy Number ◽  
Equation Model ◽  
Temperature Fields ◽  
Thermal Conductivity Ratio ◽  
Fluid Temperature ◽  
Thermal Boundary Conditions ◽  
Constant Wall Heat Flux ◽  
Non Equilibrium

This work examines analytically the forced convection in a channel partially filled with a porous material and subjected to constant wall heat flux. The Darcy–Brinkman–Forchheimer model is used to represent the fluid transport through the porous material. The local thermal non-equilibrium, two-equation model is further employed as the solid and fluid heat transport equations. Two fundamental models (models A and B) represent the thermal boundary conditions at the interface between the porous medium and the clear region. The governing equations of the problem are manipulated, and for each interface model, exact solutions, for the solid and fluid temperature fields, are developed. These solutions incorporate the porous material thickness, Biot number, fluid to solid thermal conductivity ratio and Darcy number as parameters. The results can be readily used to validate numerical simulations. They are, further, applicable to the analysis of enhanced heat transfer, using porous materials, in heat exchangers.

Assessment of Thermal Non-Equilibrium Condition on Heat Transfer through a Channel Lined with Porous Media – Constant Wall Temperature

2011 ◽  
Vol 312-315 ◽  
pp. 33-38
Author(s):  
M. Abkar ◽  
P. Forooghi ◽  
A. Abbassi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Porous Layer ◽  
Biot Number ◽  
Equilibrium Condition ◽  
Solid Phase ◽  
Local Thermal Equilibrium ◽  
Thermal Conductivity Ratio ◽  
Constant Wall Temperature ◽  
Non Equilibrium

In this paper, forced convection in a channel lined with a porous layer is investigated. The main goal is to assess the effect of local thermal non-equilibrium condition on overall heat transfer in the channel. The effects of thermal conductivity of solid and thickness of porous layer are also studied. Flow assumed to be laminar and fully developed. The Brinkman-Forchheimer model for flow as well as the two equation energy model is used. The results showed that when the problem tends to local thermal equilibrium condition, heat transfer is enhanced due to heat conduction through solid phase. Another factor, which can facilitate the heat transfer, is the increase of the thermal conductivity of solid material. This trend is sensitive to the thickness of porous layer and modified Biot number, which is a measure (criterion) of local fluid to solid heat transfer. As thickness and modified Biot number increase, the Nusselt number becomes more sensitive to the thermal conductivity ratio.

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