Precipitation (also called reactive crystallization) processes are widely employed in the chemical industry in a variety of reactors and for different purposes. The properties and quality of the resulting particulate product are highly dependent on the mixing conditions in the reactor, since precipitation reactions are mostly fast: the reaction time is usually of the order of or shorter than the mixing time. Therefore, experimental and numerical investigations of precipitation processes under different hydrodynamic conditions constitute an interesting topic. In this work, precipitation of barium sulfate (BaSO4) is numerically investigated in two different tubular reactors, taking micromixing effects into account. Different models are employed with an increasing level of complexity. These models and the reaction kinetics are first explained. RANS-based axisymmetric computations are performed using the industrial CFD code FLUENT 6.3 at steady-state. The results of the simulations are then presented and discussed in detail. Moreover, quantitative comparisons with experimental data obtained from literature are also employed for validation. Finally, concluding remarks and possible model improvements are listed.