The use of Discrete Element Method (DEM) modelling is rapidly expanding as a modelling tool to analyse particulate processes and to address technological needs in various aspects of pharmaceutical, food and detergent processing industries. Examples include estimation of parameters that are difficult to measure or quantify experimentally (e.g. internal flow fields and mixing patterns) and facilitating the scale-up of particulate processes from laboratory to pilot plant. This article compares DEM simulations of particle flow in a paddle mixer to experimental measurements using Positron Emission Particle Tracking (PEPT). Good qualitative agreement is shown between DEM and PEPT in terms of flow patterns inside the mixer. Quantitative comparison of PEPT measurements and DEM analyses shows reasonable agreement in terms of velocity distribution. In general, the DEM is shown to be capable of predicting the dynamics of the particulate flow inside the mixer. (c) 2010 Elsevier B.V. All rights reserved.