In this work, a two dimensional sway-sloshing for a partially filled rectangular tank is modeled by solving Euler's equation of motion utilizing Weakly Compressible Smoothed Particle Hydrodynamics (WCSPH) method. A special treatment is introduced for the free surface particles which is an hybrid combination of Monaghan's  XSPH velocity variant algorithm with updated velocities (VXSPH) and artificial particle displacement (APD) algorithm . The hybrid treatment presented here provides an artificial surface tension force for free surface particles thereby impeding the escape of individual particles from the free surface and keeping these particle being attached to the free surface. The time histories of free surface elevations on the left side wall of the rectangular tank are compared with experimental and numerical results available in the literature. It is shown that the VXSPH+APD treatment significantly improves the accuracy of the numerical simulations for violent flows with a free surface and lead to the results which are in very good agreement with experimental and numerical findings of the literature.