<p>In recent years, an extensive study has focused on the effects of various factors associated with the membrane support layer such as the size of the pores, porosity, thickness, hydrophobicity, and hydrophilicity, through both theoretical and empirical approaches. Along with numerical and analytical modeling, these variables are described by various two- and three-dimensional models, which have also developed for these parameters and variables. For engineering the selective layer, different categories of materials based on various morphologies, dimensions, or porosity were used as interlayers. Regarding the interlayers, there are relatively inconsistent reports in the literature and publications, primarily due to a lack of research and modeling. By modeling the influence of interlayers in thin film composite membranes, an innovative insight could be provided for optimizing other membrane processes. As a result, this research emphasizes the modeling and discussion of interlayers and their performance, particularly in the forward osmosis process, where scientific data and modeling are lacking. In addition to discussing the funnel and gutter effect carried out by the interlayers present in all membrane processes, modeling the impacts of the interlayer in the forward osmosis process will provide novel perspectives that could influence other processes.</p>