Fluid Mechanics: Newtonian and Non-Newtonian Fluids

This lecture introduces the concepts of Newtonian and non-Newtonian fluids, focusing on their behavior under shear stress. The instructor discusses the relationship between shear stress and shear strain rate, emphasizing the characteristics of Newtonian fluids such as water and air. The lecture highlights the differences between Newtonian and non-Newtonian fluids, using examples like cornstarch and silly putty to illustrate shear thickening and shear thinning behaviors. The instructor explains how to solve a flow problem involving two parallel plates and a solid plate in between, applying Newton's second law to establish force balance. The discussion includes deriving shear stress equations for different fluids and determining the velocity of the middle plate based on the viscosities of the fluids involved. The lecture concludes with a summary of the importance of understanding fluid behavior in engineering applications, particularly focusing on Newtonian fluids while acknowledging the existence of non-Newtonian effects.