Many chemical processes, such as polysilicon production in fluidized beds, can be improved by elimination of bubbles. Theory suggests that this can be done using coarse particles in place of Geldart B particles used to-day. CFD simulations using a mixture of 3.5 mm and 5 mm glass beads show that in a large bed this coarse mixture fluidizes without bubble formation over a large range of gas velocities. Visual observations and measurements in a two-dimensional bed confirm this discovery. Both CFD computations and experiments in small diameter beds show that this mixture undergoes slugging, as expected for fluidization in small diameter beds. For B particles a bottom bubble-less layer is computed. (c) 2013 Elsevier Ltd. All rights reserved.