Three-dimensional printing (3DP), also known as additive manufacturing (AM), has rapidly evolved over the past few decades. Researchers around the globe have been putting their efforts into AM processes improvement and materials development. One of the most widely used extrusion-based technology under AM processes is Fused Deposition Modeling (FDM), also known as Fused Filament Fabrication (FFF). Numerical simulation tools are being employed to predict the FFF process complexities and material behavior. These tools allow exploring candidate materials for their potential use in the FFF process and process improvements. The prime objective of this study is to provide a comprehensive review of state-of-the-art scientific achievements in numerical simulations of the FFF process for polymers and their composites. The first section presents an in-depth discussion of the FFF process's physical phenomena and highlights the multi-level complexity. The subsequent section discusses the research efforts, specifically on numerical simulation techniques reported in the literature for simulation of the FFF process. Finally, conclusions are drawn based on the reviewed literature, and future research directions are identified.
Keywords: 3D printing; additive manufacturing; computational fluid dynamics; computational modeling; simulation technique.