- Three dimensional numerical simulations of particles motion in a given geometry pneumatic conveying system are conducted in order to obtain a better understanding of the attrition process. A new and innovative procedure of implementing empirical comminution functions (Kalman etal. in Gran Mat 11:253--266, 2009) into DEM-CFD simulations was used and modified. The comminution functions include: initial strength distribution, selection function, breakage function, equivalence function and fatigue function. The implementation involves converting the probability comminution functions into individual particle properties by a random method and then converting the velocity dependent comminution functions into strength-dependent ones. The predictions of the numerical simulations are used to analyze the flow field characteristics and the size reduction process.