Non-Newtonian fluid mechanics in engineering

This review critically examines the role of non-Newtonian fluid mechanics across engineering systems, with particular emphasis on how knowledge developed in process industries can be applied and re-evaluated in marine technology. The paper first outlines the rheological framework commonly used to describe non-Newtonian behavior, including shear-dependent, yield-stress, viscoelastic, and thixotropic constitutive models, together with key dimensionless groups relevant to engineering interpretation: the Reynolds number in its generalized form, the Bingham number, the Deborah number, and the Weissenberg number. It then reviews representative engineering applications in process transport, drilling fluids, nanofluids, and additive manufacturing, not as isolated examples but as sources of cross-sector lessons for marine systems. Special attention is given to maritime applications, including polymer-based drag reduction, brash-ice interaction, dredging slurries, heavy fuel oil handling, lubrication, firefighting foams, and adaptive damping systems. The review addresses bottlenecks in experimental characterization, computational modeling, and scale-up, with acknowledgment of where current models become uncertain or application-dependent. The available evidence suggests that the principal engineering value of non-Newtonian fluids lies in functions such as drag reduction, suspension stability, restartpressure control, damping, and flow assurance; however, these benefits depend strongly on constitutive-model selection, parameter definition, formulation, and operating conditions. By integrating fundamental rheology with applicationoriented comparison, this paper aims to provide a practically useful synthesis for engineers working at the interface of process and marine systems.