ARTICLE:

• HETEROGENEOUS POROUS MEDIA AS MULTISCALE STRUCTURES FOR MAXIMUM FLOW ACCESS  download article

Sylvie Lorente
Laboratory of Materials and Durability of Constructions, INSA-UPS, Department of Civil Engineering, National Institute of Applied Sciences, 135 Avenue de Rangueil, 31077 Toulouse, France

Adrian Bejan
Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708-0300, USA

ABSTRACT

Natural porous structures are heterogeneous, with multiple scales that are distributed nonuniformly. Few large pores (fissures, channels, cracks) are accompanied by numerous finer channels. Can this type of flow architecture be attributed to a principle of maximization of global flow access? Features similar to those of multiscale porous structures are exhibited by tree-shaped flow structures. Trees have been deduced from the maximization of flow access between a point and a volume, a point and an area, and a point and a curve (e.g. circle). In this paper we invoke the same principle, and consider fundamentally the question of how to bathe with minimal flow resistance a micro-channel structure that globally behaves as a porous medium. We develop completely new multi-scale configurations that guide the flow from one side of the porous structure to the other (line to line, and plane to plane), and show analytically the advantages of tree structures over the usual stacks of parallel micro-channels. The ‘porous medium’ that has tree-shaped labyrinths is heterogeneous, with multiple scales that are distributed nonuniformly. These features invite comparisons with the design of natural porous structures.

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