Granular materials are prevalent in natural and industrial processes, such as landslides, powder flow, and pharmaceutical manufacturing. When subjected to shear forces, these materials exhibit temporary kinematic fields. This research delves into the length scale of these irregularities by simulating plane shear flows and evaluating local grain velocity, fluctuations, and deformation patterns [1-3]. We observe a broad distribution of these variables, particularly at low inertial numbers, which is ascribed to the development of spatial correlations at lower inertial numbers. A characteristic length scale is introduced to quantify these heterogeneities, and the size of a representative elementary volume (REV) is determined based on the inertial number values [4]. This size ranges from a few grain diameters at high inertial numbers to several dozen grain diameters at low inertial numbers. Understanding the representative elementary volume size is essential for refining theories related to granular flow behavior as a continuum to micro-properties [4]. The findings of this study are particularly valuable for enhancing the understanding of non-local effects at the continuum scale. By incorporating these insights, future research can advance continuum models for granular flows by investigating plastic deformation fields under shear forces. These fields are predicted to form "soft" zones where particles experience plastic deformation and "hard" zones where no plastic events have occurred. This distinction between soft and hard zones will further improve our ability to model and predict the complex behavior of granular materials under various conditions, leading to more effective applications in natural and industrial processes.