Rainfall simulation in centrifuge models is important for modelling soil-atmosphere interactions. However, the presence of Coriolis force, drag forces, evaporation and wind within the centrifuge may affect the distribution of rainfall over the model. As a result, development of appropriate centrifuge rain simulators requires a demanding process of experimental trial and error. This paper highlights the key factors involved in controlling rainfall in centrifuge simulations, develops a mathematical model to simulate rainfall within a centrifuge and shows how to calibrate it experimentally. Finally, the paper summarises some important factors that should be considered in the development of rainfall simulators for centrifuges.