This paper presents numerical simulations using an open boundary algorithm with modified dynamic boundary condition (mDBC) for weakly compressible smoothed particle hydrodynamics models from particle-based code Dualsphysics. The problems of piping erosion in earth dams are aimed at studying the algorithm. The case 2D model of fluid flow past around a fixed cylinder is simulated, where various values of Reynold's numbers (Re 20 to Re 100) and different viscosity terms are considered. A constant velocity with different values of viscosity for generating various Reynold's numbers is modeled. The interaction between solid particles of the cylinder and fluid particles is concerned, the cylinder is affected by the hydrodynamics force caused by the flow of fluid particles. The solid particles of the cylinder are the observation points to obtain force and pressure due to the hydrodynamics forces. As a result of the simulation which is to show the capability to model 2D fluid flow with various Reynold's numbers. Drag coefficient, lift coefficient, and Strouhal number are compared to the previous work from literature. © 2024 American Institute of Physics Inc.. All rights reserved.