This study proposes a simulation method for incompressible gas flow laden with small solid particles. It is based on a Vortex in Cell (VIC) method, which was originally developed to simulate incompressible single-phase flows. The proposed VIC method discretizes the gas vorticity field into vortex elements and computes the time evolution of the two-phase flow by calculating the behavior of the vortex element as well as the particle motion with the Lagrangian approach. This study also applies the VIC method to simulate a free fall of small solid particles in an unbounded air. The particles, initially arranged within a spherical region in a quiescent air, are made to fall, and their fall induces the air flow around them. The interactions between the particle motion and the air flow are favorably compared with the existing measured and simulated results, demonstrating the validity of the proposed VIC method. (C) 2012 Elsevier B.V. All rights reserved.