Solid sponges are open-celled foams usually made of metal or ceramic materials. Due to their continuous solid structure, large specific surface area and high porosity, they are promising components for highly efficient heat exchanger applications with relatively low pressure drop.
In this work, CFD simulations on the single-phase fluid flow through solid sponges have been carried out in order to understand the underlying momentum and heat transfer mechanisms within such complex porous media. The simulation geometry is derived from micro computed tomography (µCT) scans and is embedded into a surrounding homogenous porous medium which reproduces the sponge’s effective hydrodynamic and thermal properties. This procedure enables a realistic boundary condition specification at the borders of the scale resolved region while still keeping computational cost at a reasonable level. The results obtained for the pressure drop and heat transfer coefficient showed good agreement with corresponding experimental data from previous studies and literature data, confirming the reliability of this CFD modelling approach . Besides, the presented CFD approach also includes the heat transfer modelling of the solid structure which enables a detailed conjugate heat transfer analysis of the porous medium.
Furthermore, this setup is applied to examine further porous structures consisting of ideal periodic unit cells (for example cubic cells and Kelvin cells). Their resulting pressure drops are calculated as well as the contributions caused by form drag and skin friction drag. The dimensionless heat transfer coefficients and geometrical characteristics are also analyzed and compared to the ones obtained for the real sponges. The following in-depth analysis of local transport phenomena allows the identification of crucial geometrical parameters that influence the performance of the investigated structures. Obtaining this information is an important step towards an improved understanding of the flow characteristics and the methodical design of such porous media.
 S. Meinicke, Th. Wetzel, B. Dietrich (2017). ’Scale-resolved CFD modelling of single-phase hydrodynamics and conjugate heat transfer in solid sponges’. Int. J. Heat Mass Tran (108) 2017. pp. 1207-1219