In order to numerically simulate primary atomization a fully three-dimensional code based on the meshless, Lagrangian Smoothed Particle Hydrodynamics method has been developed and validated for various test cases. One of the main advantages of this approach compared to meshbased simulation methods is the inherent interface advection without the need for interface markers or interface capturing techniques. The present paper focuses on the capability of our code to accurately capture multiphase flow phenomena. For validation of the method regarding shear-driven flows the unsteady evolution of a Couette flow has been simulated successfully. Furthermore, surface tension effects in a multiphase system with a large density ratio of the gas-liquid mixture are modeled accurately. Moreover, the simulation of the disintegration process of a liquid film, driven by the surrounding air flow, at an atomizer edge has been performed. The results demonstrate the promising potential of the method to numerically predict the entire primary atomization in complex airblast atomizers.