In this study, three different oxidation-driven soot aggregate fragmentation models with 1:1, 2:1, and 10:1 fragmentation patterns are developed and implemented into a laminar coflow ethylene/air diffusion flame, together with a pyrene-based soot model and a sectional aerosol dynamics model. It is found that the average degree of particle aggregation (np) in the soot oxidation region is not correctly predicted if oxidation-driven aggregate fragmentation is neglected; whereas the incorporation of aggregate fragmentation significantly improves the np prediction in the soot oxidation region. Similar results are obtained using the 1:1 and 2:1 fragmentation patterns. However, as the pattern ratio increases to 10:1, appreciable difference in the predicted np is observed. As the pattern ratio becomes larger, the fragmentation effect diminishes and the predicted np approaches that of the original model neglecting fragmentation. ; peer reviewed: yes ; NRC Pub: yes