Ironmaking technology is currently focused on the introduction of the decreased reducing agent operation of a blast furnace in order to decrease CO2 emissions. Because the coke ratio is reduced in this operation, causing a huge pressure drop, it has become increasingly important to understand the in-furnace phenomena using the non-empirical method. In this study, the DEM-CFD simulation was carried out to analyze the heat and mass transfer between the gaseous phase and the particles in a packed bed. In particular, the effect of recently proposed helical structure of coke and ore layers was compared with the traditional layer-by-layer structure. This comparison shows that the helical structure is effective for the smooth gas flow in the packed bed. It was found that the increase of the gas flow rate in a large grain size coke layer, would not affect the total permeability of the packed bed. Since the helical structure decreases the amount of inflow of the gaseous phase to the ore bed, the reduction rate of this ore tends to decrease the thickness of the layered structure, but this effect is relatively small. The helical structure becomes more permeable, if a thicker layer is maintained even under the decreased coke ratio condition. (C) 2015 Elsevier Ltd. All rights reserved.