Atomization of liquid fuel has a direct impact on the production of pollutant emission in engineering propulsion devices. Due to the multiple challenges in experimental investigations, motivation for numerical study is increasing on liquid/gas interaction from injection till dispersed spray zone. Our purpose is to increase the accuracy of the treatment of droplets in atomized jet, which are typically 1000 times smaller than the injection size. As the size of the droplets reduces with the primary breakup of liquid fuel, it is increasingly challenging to track the interface of the droplets accurately. To solve this multiscale issue, a coupled tracking Eulerian-Lagrangian Method is proposed. This communication focuses on the criteria of transformation of this coupling from interface captured droplets to Lagrangian particles. From the literature, interaction criteria of transformation are all geometric, implementation of physical parameter is made in this communication. Those criteria are discussed in academic cases and a liquid jet atomization.