Axial segregation in horizontal rotating drums is studied focusing on the effect of wall roughness and geometry. The problem is tackled both numerically and experimentally. Simulations are based on a cellular automata (CA) approach using rules derived from experiments and the experimental validation of the simulated phenomenology is given for noteworthy cases. Notwithstanding the simple model used to implement CA simulations, good qualitative agreement with experiments is observed and many features of the segregation process are captured. These include the major role of fluctuations of concentration on the onset of axial segregation, the overall exponential decrease of the number of segregated bands due to their progressive merging and the long lasting character of the segregation dynamics. Simulations and experiments also suggest a simple but effective strategy to reduce axial segregation which can be potentially used to contrast segregation in industrial mixing of free flowing powders. (C) 2013 Elsevier Ltd. All rights reserved.