Comparison of Pore-Level and Volume-Averaged Computations in Highly Conductive Spherical-Void-Phase Porous Materials

Vu, Jeremy; Straatman, Anthony G.

doi:10.1007/s11242-018-1082-6

Cited by 8 publications

(4 citation statements)

References 29 publications

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“…For multiphase flow conditions, additional unknown parameters, such as the relative permeability coefficient for each phase and the capillary pressure relationship, need to be specified [8]. To solve the governing equation and determine the unknown values, DNS or experimental studies are necessary [9]. Therefore, DNS is essential not only for understanding the complex and unpredictable flow structure within the porous medium but also for resolving the volume averaging equations.…”

Section: Introductionmentioning

confidence: 99%

Multiphase flow simulation in hybrid porous structure

Nimvari,

Gibbons

2024

J. Phys.: Conf. Ser.

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Recent research has primarily focused on creating biporous and hybrid porous structures with multiple pore sizes and length scales to optimize capillary pressure and permeability. Despite numerous experimental investigations on biporous and hybrid media, there is a noticeable absence of numerical simulations that explore the multiphase flow within these media. Therefore, the present study aims to conduct a pore-scale numerical simulation of two-phase flow in a biporous structure. The biporous structure is proposed by arranging clusters of solid particles in a staggered regular pattern, with each cluster consisting of closely packed particles. The dimensions and characteristics of the simulated structure are based on previous experimental literature on biporous and hybrid media. A monoporous structure simulation is also included for comparison with biporous results. ANSYS Fluent is utilized to carry out the numerical simulations of capillary pumping flow. The simulation results indicate that the permeability and average capillary pressure of the biporous media are four times and over one and a half times higher, respectively, compared to those of the monoporous media. The presence of smaller pathways within each cluster of a biporous and hybrid porous media enhances the capillary effect in comparison to conventional monoporous structures. Additionally, the larger pores between the clusters contribute to a higher permeability of the hybrid porous structure. As a result, the combined effect of increased capillary action and higher permeability leads to improved performance of the hybrid porous structure. Overall, the proposed simplified biporous geometry accurately models fluid flow in real, complex biporous and hybrid structures.

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Section: Introductionmentioning

confidence: 99%

Multiphase flow simulation in hybrid porous structure

Nimvari,

Gibbons

2024

J. Phys.: Conf. Ser.

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“…They observed reasonable agreement between the prediction results of the pore scale and volume average. Vu and Straatman (2018) discussed the pore level and volume averaged computations in highly conductive spherical-void-phase porous materials. Hangi et al (2020) provided a numerical study to compare the heat transfer results of volume average method with determined effective transport coefficients to those of a pore scale level simulation for the dual-scale porous structures.…”

Section: Introductionmentioning

confidence: 99%

The effect of porosity and number of unit cell on applicability of volume average approach in closed cell porous media

Wang

Zheng

Zhang

et al. 2021

HFF

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Purpose The purpose of this study is to investigate the applicability of volume average which is extensively used for analyzing the heat and fluid flow (both for single-phase and solid/liquid-phase change) in a closed cell porous medium numerically. Design/methodology/approach Heat conduction equations for the solid frame and fluid (or phase change material) are solved for pore scale and volume average approaches. The study mainly focuses on the effect of porosity and the number of porous media unit cell on the agreement between the results of the pore scale and volume average approaches. Findings It is observed for the lowest porosity values such as 0.3 and the number of porous media unit cell as 4 in heat transfer direction, the results between two approaches may be questionable for the single-phase fluid. By increasing the number of porous media unit cell in heat transfer direction, the agreement between two approaches becomes better. In general, for high porosity values (such as 0.9) the agreement between the results of two approaches is in the acceptable range both for single-phase and solid/liquid-phase change. Two charts on the applicability of volume average method for single-phase and solid/liquid-phase change are presented. Originality/value The authors’ literature survey shows that it is the first time the applicability of volume average which is extensively used for analyzing the heat and fluid flow in a closed cell porous medium is investigated numerically.

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“…These simulations can be used to obtain integral quantities characterizing the resistance to fluid passage, convective exchange and thermal dispersion, all of which are required for analogous simulations conducted using the volume-averaged (porous-continuum) approach. In addition to flow resistance and interstitial heat exchange, accurate information must be provided to characterize the solid phase conduction, which because of the complex shape, is a function of both solid-phase conductivity and a conduction shape factor, which characterizes the departure of the conduction path from being straight and of uniform cross-section [5][6].In the present study, spherical-void-phase representative elemental volumes developed using the Discrete Element approach described in Dyck & Straatman [7] were produced over the range of porosities 0.70 ≤ ε ≤ 0.85 and for pore diameters of 400 µm and 800 µm. Simulations of conduction-only through the solid domain were then conducted using the commercial software CFX to establish conduction shape factors using the approach of Fleet and Straatman [6].…”

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confidence: 99%

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confidence: 99%

The Impact Of Conduction Shape Factor In Volume Averaged Calculations Of Heat Transfer In Permeable Porous Materials

Straatman¹,

Fleet²

2022

Proceedings of the 8th World Congress on Mechanical, Chemical, and Material Engineering

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Porous materials like metal and graphitic foams are seeing increased use in heat transfer devices due to their high solidphase conductivity and area-to-volume ratios. The internal structures of these materials can be extremely complex, but accurate characterization of the foam properties in terms of permeability, inertial losses, interstitial exchange and effective conductivity are critical for being able to consider such materials in design and application. Recent literature exists for characterizing permeable porous materials by conducting pore-level simulations on idealized geometric models [1-2] or geometric models generated by scanning samples of the porous media [3][4]. In such cases, a given geometric structure is discretized and simulations are conducted to obtain direct solutions to the mass, momentum and energy equations under laminar or turbulent flow conditions. These simulations can be used to obtain integral quantities characterizing the resistance to fluid passage, convective exchange and thermal dispersion, all of which are required for analogous simulations conducted using the volume-averaged (porous-continuum) approach. In addition to flow resistance and interstitial heat exchange, accurate information must be provided to characterize the solid phase conduction, which because of the complex shape, is a function of both solid-phase conductivity and a conduction shape factor, which characterizes the departure of the conduction path from being straight and of uniform cross-section [5][6].In the present study, spherical-void-phase representative elemental volumes developed using the Discrete Element approach described in Dyck & Straatman [7] were produced over the range of porosities 0.70 ≤ ε ≤ 0.85 and for pore diameters of 400 µm and 800 µm. Simulations of conduction-only through the solid domain were then conducted using the commercial software CFX to establish conduction shape factors using the approach of Fleet and Straatman [6]. Simulations of conjugate heat transfer were also conducted to provide validation for similar simulations conducted using the porous continuum (volume-averaged) approach. The volume-averaged simulations were conducted using an in-house, conjugate domain, thermal non-equilibrium CFD code described in Betchen et al. [8], but modified to include the conduction shape factor (F). The simulations including F are shown to be in excellent agreement across the full range of heating and Re D considered. The results also show that without including F, the volume-averaged simulations over-predict the heat transfer by as much as 40% owing to the over-estimation of the effective solid-phase conductivity. Of important note is that porelevel calculations of conjugate heat transfer require more than 25 times the CPU effort compared to those conducted using the volume-averaged approach with F, which illustrates the important utility of volume-averaged heat transfer calculations in porous materials.

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Comparison of Pore-Level and Volume-Averaged Computations in Highly Conductive Spherical-Void-Phase Porous Materials

Cited by 8 publications

References 29 publications

Multiphase flow simulation in hybrid porous structure

Multiphase flow simulation in hybrid porous structure

The effect of porosity and number of unit cell on applicability of volume average approach in closed cell porous media

The Impact Of Conduction Shape Factor In Volume Averaged Calculations Of Heat Transfer In Permeable Porous Materials

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