Abstract
The development and validation of a grid-based pore-scale numerical modelling methodology applied to five different commercial metal foam samples is described. The 3-D digital representation of the foam geometry was obtained by the use of X-ray microcomputer tomography scans, and macroscopic properties such as porosity, specific surface and pore size distribution are directly calculated from tomographic data. Pressure drop measurements were performed on all the samples under a wide range of flow velocities, with focus on the turbulent flow regime. Airflow pore-scale simulations were carried out solving the continuity and Navier–Stokes equations using a commercial finite volume code. The feasibility of using Reynolds-averaged Navier–Stokes models to account for the turbulence within the pore space was evaluated. Macroscopic transport quantities are calculated from the pore-scale simulations by averaging. Permeability and Forchheimer coefficient values are obtained from the pressure gradient data for both experiments and simulations and used for validation. Results have shown that viscous losses are practically negligible under the conditions investigated and pressure losses are dominated by inertial effects. Simulations performed on samples with varying thickness in the flow direction showed the pressure gradient to be affected by the sample thickness. However, as the thickness increased, the pressure gradient tended towards an asymptotic value.
Highlights
Open-cell metal foams have unique properties such as high surface area per unit volume, low density, high stiffness and good energy absorption, making them well suited to a diverge range of engineering applications (Banhart 2001)
A steady-state pore-scale simulation took between 30 min to 2 h of computing time to achieve convergence depending on the mesh size
The pressure measurements were taken under a range of u D = 2.3–26 m/s, and pore-scale simulations were performed for u D = 5–25 m/s
Summary
Open-cell metal foams have unique properties such as high surface area per unit volume, low density, high stiffness and good energy absorption, making them well suited to a diverge range of engineering applications (Banhart 2001). The foam’s intricate geometry makes experimental acquisition of detailed flow data troublesome, and normally only macroscopic quantities such as pressure drop can be measured, drawing many researchers to employ numerical pore-scale simulations in order to overcome such limitations. There are essentially two classes of numerical approaches employed in pore-scale simulations. The second is direct simulation, where the flow governing equations are computed directly in the pore space geometry using methods based on first principles. Such type of approach requires an explicit representation of the solid matrix geometry. This paper is concerned with direct pore-scale simulations performed in commercial open-cell metal foams
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