Complex fluid dynamics refers to the study of fluids that exhibit non-Newtonian behavior, such as viscoelasticity, shear-thinning, and shear-thickening. These fluids do not follow the simple linear relationship between shear stress and shear rate that Newtonian fluids do. In the context of nanotechnology, understanding complex fluid dynamics is crucial for optimizing the performance and functionality of nanoscale systems and devices.