Methods for simulating a downhole drilling operation include estimating the geometry, i.e., the shape, size of rock chips generated by engagement of a drill bit with a geologic formation. Each cutting element on the drill bit may produce rock chips of different geometry, and the geometry of rock chips generated by a particular cutting element may change over a predetermined interval. The geometry and other properties rock chips predicted for an interval may be recorded, and a distribution may be calculated based on categorizing each of the predicted rock chips into predefined categories and determining the relative number of rock chips in each category. The distribution may be useful in drill bit design, determining required mud flow characteristics for a drilling operation, and facilitating rotation of a drill string by preventing undesirable interactions of the rock chips with the drill bit and other downhole equipment.