Inertial separation of dust from air and gas streams using settling or baffle chambers is simple and cost effective. In order to increase the effectiveness of a single chamber, AerosolTrap has been developed. This new device uses four chambers in series, stacked on top of each other. The aim of the present study is to examine the performance of AerosolTrap and investigate if computational fluid dynamics (CFD) simulations can be used as a tool to optimize its geometry. Simulations and validating laboratory experiments have been performed using different flows and different mix of particles. This article describes the methodology used and presents results showing that CFD simulations predict the general characteristics of the AerosolTrap well but underestimate the separation coefficient slightly.