Abstract Inhibiting cavity formation by mixing coarse particles into a moving bed was investigated by the discrete element method. The results indicated that coarse particles contributed to inhibiting the cavity formation in a moving bed, especially when the wall friction coefficients of coarse particles were lower than those of fine particles. To enhance the effect of coarse particles on cavity formation in the moving bed, the coarse particles should be dispersed in the bed when the wall friction coefficients of coarse particles were the same as those of fine particles, but should be concentrated at wall when the wall friction coefficients of coarse particles were significantly smaller than those of fine particles.
