Flow Maldistribution in Microsystems: Description and Effects

Flow maldistribution is a fluid-management problem of interest in engineering. It consists in the non-uniform distribution of various flows in industrial applications like multiple accesses, manifolds, bifurcations, spreaders, etc., where the fluid currents separate, detach and reattach, break from the main body of the stream and splash within the conducts, etc. Several effects in the operation of most systems and apparatus where it occurs are common, including the interruption of fluid currents, malfunctioning, and high energy consumptions. The problem at industrial scale has been identified and treated mainly through empirical considerations, but no totally solved. It has been scarcely investigated however, in micro-technology applications with unforeseeable situations in theses very small area/volume scales, with appealing engineering tasks to solve. In any case, detailed analyses must be conducted using fluid mechanics models with experimental validation. In this paper the most relevant aspects of flow maldistribution in micro-systems where intense heat and mass transfer occur, are described. A review of their consequences and the current trends for their remediation, are presented. Examples in MEMS, fuel cells, micro-heat exchangers and micro-structured chemical reactors, are considered.