In an effort to simulate the field evaporation process in atom probe tomography, Rolland et al. developed a model, namely RRM, which was considerably successful in simulating the evaporation mechanisms of ions as they leave the tip and hit the detector. But the ubiquitous mechanism of rolling up was not considered in this model which perhaps accounts for the discrepancies in the simulated and experimental results. This present work, in addition to incorporating the roll-up mechanism in RRM, also aims to study and quantify the level of randomness this and perhaps other relatively less significant distortion mechanisms adds to the evaporation process.