A comparative study of Knudsen diffusion in cellular metals

This paper addresses Knudsen diffusion in cellular metals. Knudsen diffusivities for air at room temperature are calculated for a representative cross-section of the different types of cellular materials: a sintered fibre structure, a lotus-type porous metal, a sintered metallic hollow sphere structure and a M-Pore® aluminium foam. The geometrical discretization of the calculation models is based on computed tomography data. This approach is essential in order to address the complex geometries of cellular metals. In total, seven calculation models with porosities ranging from 0.26 to 0.92 are considered. In addition, anisotropy is investigated by determining directional components of the Knudsen diffusivity.