scholarly journals An experimentally validated and parameterized periodic unit-cell reconstruction of open-cell foams

2011 ◽  
Vol 109 (10) ◽  
pp. 103519 ◽  
Author(s):  
P. De Jaeger ◽  
C. T’Joen ◽  
H. Huisseune ◽  
B. Ameel ◽  
M. De Paepe
Keyword(s):  
Unit Cell ◽  
Open Cell ◽  
Open Cell Foams ◽  
Periodic Unit Cell

scholarly journals Simulation of Thermal Transport in Open-Cell Metal Foams: Effect of Periodic Unit Cell Structure

2006 ◽  
Author(s):  
Shankar Krishnan ◽  
Suresh V. Garimella ◽  
Jayathi Y. Murthy
Keyword(s):  
Thermal Transport ◽  
Pore Space ◽  
Cell Structure ◽  
Flow Characteristics ◽  
Metal Foams ◽  
Unit Cube ◽  
Unit Cell ◽  
Face Centered Cubic ◽  
Open Cell ◽  
Periodic Unit Cell

Direct simulation of thermal transport in open-cell metal foams is conducted using different periodic unit cell geometries. The periodic unit cell structures are constructed by assuming the pore space to be spherical and subtracting the pore space from a unit cube of the metal. Different types of packing arrangement for spheres are considered - Body Centered Cubic, Face Centered Cubic, and the A15 lattice (similar to a Weaire-Phelan unit cell) - which give rise to different foam structures. Effective thermal conductivity, pressure drop and Nusselt number are computed by imposing periodic boundary conditions for aluminum foams saturated with air or water. The computed values compare well with existing experimental measurements and semi-empirical models for porosities greater than 80%. The effect of different foam packing arrangements on the computed thermal and fluid flow characteristics is discussed. The capabilities and limitations of the present approach are identified.

The Linear Elastic Properties of Open-Cell Foams

1988 ◽  
Vol 55 (2) ◽  
pp. 341-346 ◽  
Author(s):  
W. E. Warren ◽  
A. M. Kraynik
Keyword(s):  
Young’S Modulus ◽  
Elastic Properties ◽  
Cross Section ◽  
Elastic Constants ◽  
Volume Fraction ◽  
Cellular Materials ◽  
Unit Cell ◽  
Open Cell ◽  
Linear Elastic ◽  
Open Cell Foams

A theoretical model for the linear elastic properties of three-dimensional open-cell foams is developed. We consider a tetrahedral unit cell, which contains four identical half-struts that join at equal angles, to represent the essential microstructural features of a foam. The effective continuum stress is obtained for an individual tetrahedral element arbitrarily oriented with respect to the principal directions of strain. The effective elastic constants for a foam are determined under the assumption that all possible orientations of the unit cell are equally probable in a representative volume element. The elastic constants are expressed as functions of compliances for bending and stretching of a strut, whose cross section is permitted to vary with distance from the joint, so the effect of strut morphology on effective elastic properties can be determined. Strut bending is the primary distortional mechanism for low-density foams with tetrahedral microstructure. For uniform strut cross section, the effective Young’s modulus is proportional to the volume fraction of solid material squared, and the coefficient of proportionality depends upon the specific strut shape. A similar analysis for cellular materials with cubic microstructure indicates that strut extension is the dominant distortional mechanism and that the effective Young’s modulus is linear in volume fraction. Our results emphasize the essential role of microstructure in determining the linear elastic properties of cellular materials and provide a theoretical framework for investigating nonlinear behavior.

scholarly journals Periodic unit cell reconstruction of porous media: Application to open-cell aluminum foams

2007 ◽  
Vol 101 (11) ◽  
pp. 113538 ◽  
Author(s):  
Camille Perrot ◽  
Raymond Panneton ◽  
Xavier Olny
Keyword(s):  
Porous Media ◽  
Unit Cell ◽  
Aluminum Foams ◽  
Open Cell ◽  
Periodic Unit Cell

scholarly journals Simulation of Thermal Transport in Open-Cell Metal Foams: Effect of Periodic Unit-Cell Structure

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Shankar Krishnan ◽  
Suresh V. Garimella ◽  
Jayathi Y. Murthy
Keyword(s):  
Thermal Transport ◽  
Pore Space ◽  
Cell Structure ◽  
Flow Characteristics ◽  
Metal Foams ◽  
Unit Cube ◽  
Unit Cell ◽  
Face Centered Cubic ◽  
Open Cell ◽  
Periodic Unit Cell

Direct simulation of thermal transport in open-cell metal foams is conducted using different periodic unit-cell geometries. The periodic unit-cell structures are constructed by assuming the pore space to be spherical and subtracting the pore space from a unit cube of the metal. Different types of packing arrangement for spheres are considered—body centered cubic, face centered cubic, and the A15 lattice (similar to a Weaire-Phelan unit cell)—which give rise to different foam structures. Effective thermal conductivity, pressure drop, and Nusselt number are computed by imposing periodic boundary conditions for aluminum foams saturated with air or water. The computed values compare well with existing experimental measurements and semiempirical models for porosities greater than 80%. The effect of different foam packing arrangements on the computed thermal and fluid flow characteristics is discussed. The capabilities and limitations of the present approach are identified.

Direct Simulation of Transport in Open-Cell Metal Foam

2006 ◽  
Vol 128 (8) ◽  
pp. 793-799 ◽  
Author(s):  
Shankar Krishnan ◽  
Jayathi Y. Murthy ◽  
Suresh V. Garimella
Keyword(s):  
Metal Foam ◽  
Flow Characteristics ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Unit Cell ◽  
Computational Time ◽  
Small Scale ◽  
Direct Simulation ◽  
Open Cell ◽  
Periodic Unit Cell

Flows in porous media may be modeled using two major classes of approaches: (a) a macroscopic approach, where volume-averaged semiempirical equations are used to describe flow characteristics, and (b) a microscopic approach, where small-scale flow details are simulated by considering the specific geometry of the porous medium. In the first approach, small-scale details are ignored and the information so lost is represented in the governing equations using an engineering model. In the second, the intricate geometry of the porous structures is accounted for and the transport through these structures computed. The latter approach is computationally expensive if the entire physical domain were to be simulated. Computational time can be reduced by exploiting periodicity when it exists. In the present work we carry out a direct simulation of the transport in an open-cell metal foam using a periodic unit cell. The foam geometry is created by assuming the pore to be spherical. The spheres are located at the vertices and at the center of the unit cell. The periodic foam geometry is obtained by subtracting the unit cell cube from the spheres. Fluid and heat flow are computed in the periodic unit cell. Our objective in the present study is to obtain the effective thermal conductivity, pressure drop, and local heat transfer coefficient from a consistent direct simulation of the open-cell foam structure. The computed values compare well with the existing experimental measurements and semiempirical models for porosities greater than 94%. The results and the merits of the present approach are discussed.

scholarly journals Direct Simulation of Transport in Open-Cell Metal Foams

2005 ◽  
Author(s):  
Shankar Krishnan ◽  
Jayathi Y. Murthy ◽  
Suresh V. Garimella
Keyword(s):  
Metal Foam ◽  
Flow Characteristics ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Unit Cell ◽  
Small Scale ◽  
Direct Simulation ◽  
Open Cell ◽  
Semi Empirical ◽  
Periodic Unit Cell

Flows in porous media may be modeled using either a macroscopic approach, where volume-averaged semi-empirical equations are used to describe flow characteristics, or a microscopic approach, where small-scale flow details are simulated by considering the specific geometry of the porous medium. A direct simulation of the transport in an open-cell metal foam is carried out in the present study using a periodic unit cell. The foam geometry is created by assuming the pore to be spherical. The spheres are located at the vertices and at the center of the unit cell. The periodic foam geometry is obtained by subtracting the unit cell cube from the spheres. Fluid and heat flow are computed in the periodic unit cell. The objective of the present study is to obtain the effective thermal conductivity, pressure drop and local heat transfer coefficient from a consistent direct simulation of the open-cell foam structure. The computed values compare well with the existing experimental measurements and semi-empirical models. The results and the merits of the present approach are discussed.

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