NemNewtoniák

NemNewtoniák refers to non-Newtonian fluids, which are fluids that do not follow Newton's law of viscosity. In contrast, Newtonian fluids exhibit a constant viscosity regardless of the stress applied to them. For non-Newtonian fluids, viscosity changes in response to applied stress or shear rate. This means their flow behavior can be quite unusual and differs significantly from water or oil, which are common examples of Newtonian fluids.

There are several types of non-Newtonian fluids. Shear-thinning fluids, also known as pseudoplastic fluids, decrease in viscosity as shear rate increases. Ketchup and paint are everyday examples; they are thick when at rest but flow more easily when stirred or spread. Shear-thickening fluids, or dilatant fluids, exhibit the opposite behavior, increasing in viscosity with increasing shear rate. Oobleck, a mixture of cornstarch and water, is a classic example. When handled slowly, it feels like a liquid, but when squeezed or hit, it becomes solid-like.

Other categories include thixotropic fluids, which show time-dependent shear thinning, and rheopectic fluids, which show time-dependent shear thickening. Bingham plastics behave like a solid until a certain yield stress is applied, after which they flow like a liquid. Toothpaste is often cited as an example. Understanding the behavior of non-Newtonian fluids is crucial in various industrial applications, from food processing and cosmetics to the design of pipelines and hydraulic systems.