The agglomeration and breakup of flee aggregates formed in orthokinetic coagulation is examined. By considering local flow strain-rate, a breakup rate kernel is derived based on flow-induced normal stresses, The new breakup kernel is included in a population size class balance for hoc aggregates. The resulting population balance was solved numerically over a wide range of parameters to obtain a variety of flee size distributions. Results indicate that the inclusion of a breakup kernel in orthokinetic coagulation modeling eliminates the computational growth to a maximum size class, producing more realistic distributions. The breakup kernel was rigorously compared to prior research and found to be consistent with the earlier theories of coagulation agglomeration and breakup.