Diverse applications of two phase flows have attracted many researchers to the modeling and simulation of these flows. The goal of this research is to investigate and to simulate particle dynamics in an isothermal flow by means of the “Hybrid Eulerian-Lagrangian”. In multiphase flows, it is necessary to examine each phase individually, and to consider the inter-phase traort. Therefore, in the framework of the Eulerian-Lagrangian scheme, the continuous phase is studied from an Eulerian viewpoint, using Fluent software for its numerical simulations, whereas a Lagrangian viewpoint is used for simulation of disperse phase. The particle equations are complex and their analytical solutions are not possible for practical cases. Therefore, the Rk4 integration method is used to solve the particle equations. The most important part of the numerical simulation of the particle phase is the search algorithm for finding the computational element in which the particle is placed. In this research, in addition to complete surveying about these algorithms, two efficient algorithms, namely those of Blasco-Chorda and Haselbacher-Najjar where adopted due to their simplicity in coding and efficiency in computational time. For a comparison between these algorithms, two groups of problems are considered; the first group considers motion of particles in simple flow fields, for which analytical solutions of the Eulerian phase exist. The second group considers the dynamics of particles in complex flows, for which CFD solutions of the flow-fields are required. The first group includes the motion of particles exposed to gravity force, motion of particles in free and force vortex flows and motion of particles exposed to the Brownian force. The second group includes the motion of particles in a backward facing step, and motion of particles in separating cyclones. Results obtained show very good degree of accuracy and acceptable computational time for both algorithms. However, the Haselbacher-Najjar algorithm shows better performance in most cases. Keywords: Particle Tracking, Two Phase Flow, Unstructured Grids, Lagrangian Method.