This paper presents an investigation, by discrete element method simulation, of an application of gas pulsation for tackling defluidization. Particles of 0.5 mm in diameter and 2650 kg/m(3) in density were used. The state of complete defluidization was simulated by imposing an artificial interparticle attractive force on the particles. Results of this study show that gas-phase pulsation is effective in dealing with defluidization over a wide range of pulsation amplitudes and frequencies, regardless of whether the pulsation is in the form of a sinusoidal wave or square wave. (c) 2005 Elsevier Ltd. All rights reserved.