Compartment models (CMs) are widely used to capture typical hydrodynamic features of systems, generally having low computational cost. The main building blocks of the CMs are the continuous stirred tank reactor and plug flow reactor models. In this study, the hydrodynamics of two laboratory scale continuously oscillated baffled crystallizer systems were investigated: the commercially available DN15 and a scaled down version known as the DN6. CM structures were identified based on residence time distribution (RTD) measurements by direct fitting method for both the DN6 and DN15 systems, which showed superior performance compared to the traditional tank in series CM structure determination. To attain a more accurate CM calibration, the piston and pump flowrates obtained by the typical peristaltic pump configurations were thoroughly analyzed. The investigations revealed that the behavior of the systems varies based on the oscillation amplitudes and frequencies, so the number of compartments required for an adequate model was identified based on measurement with different amplitudes and frequencies. It is shown that adaptive tank in series CMs are needed to capture the measured RTD characteristics over a broad piston operation range. Not only the RTD curves but the calculated compartment numbers follow similar trends in DN6 and DN15. This enabled the generalization of the CM structure for the DN6 and DN15 systems. (C) 2020 The Author(s). Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.