Obtaining a uniform dispersion of the nanoparticles and their structural integrity in metal matrix is a prominent obstacle to use the intrinsic properties of metal matrix nanocomposites (MMNCs) to the full extent. In this study, a potential way to overcome the scientific and technical barrier of nanoparticle dispersion in high performance lightweight MMNCs is presented. The goal is to identify the shape and size of Al2O3 nanoparticle for its optimal dispersion in Al matrix. Critical velocity of solidification is calculated numerically for spherical, cylindrical and disk-shaped nanoparticles using an analytical model which incorporates drag force, intermolecular force and inertia effect. The results show that it is possible to reduce the critical solidification velocity for nanoparticle capture by 6 times with proper shape modification. (C) 2015 Elsevier B.V. All rights reserved.