Semi-analytical models for non-Newtonian fluids in tapered and cylindrical ducts, applied to the extrusion-based additive manufacturing

•A fast iterative method for the description of the flow of both Cross-WLF and Carreau fluids in straight nozzles shows higher accuracy if compared to analytical methods.•The flow of Cross-WLF and Carreau fluids in converging nozzles can be predicted calculated by means of the Jeffery-Hamel flow approximation, especially at very low taper angles and flow rates.•This theory has been applied to additive manufacturing; in particular, the extrusion of moisture-cured silicones (Carreau) and molten thermoplastic materials (Cross-WLF) has been analysed.