The modeling of coagulation kinetics in complex laminar flow

The process of orthokinetic coagulation in a complex flow was examined. A new model was developed and used to simulate orthokinetic coagulation in a multi-dimensional flow. The new model includes the effects of both agglomeration due to fluid motion and aggregate break-up from local stresses. The fluid motion that exists between two eccentrically located and rotating cylinders was used as the complex laminar flow. The flow between the eccentric cylinders has been modeled exactly by Balal and Rivlin (1977) and their solution was used in the analysis. The flow system was subsequently modeled using finite, volume elements to predict orthokinetic coagulation in the eccentric flow system. Three different methods of modeling coagulation in the flow system were examined. The differences in the modeling methods were based on the treatment of the volume elements. The first modeling technique used a volume weighted average of the local strain-rates to predict the orthokinetic coagulation. The second method treated each volume element as a separate batch reactor and a volume average of the population balance was subsequently obtained. The final modeling technique applied mass transfer between each of the elements.; The results showed that mass transfer must be included in the coagulation modeling. Further, the traditional approaches to modeling orthokinetic coagulation in a complex flow were found to in error. Specifically, the use of Camp and Stein's (1943) root-mean-square velocity-gradient failed account for the spatial variation of strain-rate in the complex flow. The modeling analysis indicates that a more comprehensive technique is required to accurately predict orthokinetic coagulation in a complex flow.