A wind deficit model for wind farms is developed in this work using finite volume method. The main question addressed here is to calculate approximately the wind speed in the vicinity of each wind turbine of a farm. The procedure followed is to solve the governing equations of flow for the whole wind farm. Spatial discretization is performed on a computational domain, using finite volume techniques. In ideal circumstances, wind speed will calculate on a fine mesh for the whole wind farm, where the effect of wind turbines is observed by means of their thrust coefficient. The end goal of this method is to assist the development of an analytical expression of an offshore wind farm wake. We focus in this work on wind deficit that can be used for better wind farm control strategies and load optimization.