Lagrangian approaches such as the Moving Particle Semi-Implicit method and Smoothed particle Hydrodynamics are the latest techniques in Computational Fluids Dynamics and have attracted the attention of many researchers. Due to the Lagrangian nature of such practices, they can simulate various problems with large deformations and a variety of boundary conditions which has led to their application in many complex engineering problems. Therefore, the accuracy of the results obtained using these methods is substantial, while various parameters affect the accuracy of the simulation. In this paper, the sensitivity of a dam-break flow simulated by the Weakly Compressible Moving Particle Semi-Implicit method associated with the particle size and Courant number is analyzed. The analysis is performed in two circumstances. First, the Courant number is fixed, and the sensitivity relative to particle size is investigated. Then, sensitivity relative to the Courant number is studied in fixed particle size. In general, it can be concluded that the smaller the particle size and Courant number, the higher accuracy and computational cost
