The present study is mainly motivated to develop an unsteady computational code which is simulating a transient behaviour of the spray injected into moderately high pressure environment (For a phenomenological study of the pressure effect on the spray, Aggarwal divided pressure range into two regimes: moderately high pressure regime and critical/supercritical regime). In order to represent the spray development, the DDM (Discrete Droplet Flow) models. Here, the Eulerian-Lagrangian formulation is used to analyze the two-phase interactions. For an accurate prediction of droplet evaporation rate in high pressure, a proper high pressure evaporation model is applied. Also, the effects of high pressure as well as high temperature are considered in the calculation of liquid and gas properties. Throughout the numerical simulation, transient thermo-fluid mechanical behaviour of spray in high pressure as well as normal pressure is traced and visualized.