Experiments and fully resolved numerical simulations are reliable, yet costly ways of designing safe and efficient flushing processes. An alternative is the use of a simplified algebraic model. In this work a model previously developed by the present authors for combinations of fluids with identical properties is extended to different fluid properties of previous and flushing fluid. A realistic range of fluid properties is determined using chocolate as an example. The results from the simplified model are compared to highly resolved numerical data. The simplified model is able to predict the flushing process well, for phases where only the removal of previous fluid near the wall is relevant. This is achieved quickly, when the previous fluid has a lower apparent viscosity than the displacing one. In the opposite case, the prediction quality of the model for the preceding phase is low and other approaches should be considered.