Viskoosne

Viskoosne is an Estonian adjective meaning viscous, used to describe liquids or semi-fluids that resist flow and deform slowly under applied stress. In physics and rheology, viscosity is the measure of this resistance, arising from internal friction between layers of the substance as it moves.

Viscosity can be described in several related terms. Dynamic (or absolute) viscosity, denoted by mu, is measured in pascal-seconds (Pa·s). Kinematic viscosity, denoted by nu, is the ratio of dynamic viscosity to density and is measured in square meters per second (m^2/s). The relationship is nu = mu / rho, where rho is density. Viscosity is a key parameter in modeling how fluids behave under forces such as shear and pressure.

Viscosity depends on temperature, pressure, composition, and the rate at which the fluid is deformed. For most liquids, viscosity decreases as temperature rises. In gases, viscosity typically increases with temperature. Fluids can also be Newtonian, with constant viscosity independent of shear rate, or non-Newtonian, where viscosity changes with shear rate or time, exhibiting behaviors such as shear-thinning or shear-thickening.

Common examples illustrate a range of viscosities: honey and thick syrups are highly viscous, while water and many alcohols are much less viscous. Viscous materials include oils, syrups, gels, and many polymers.

Applications of viscosity knowledge span lubrication, food science, cosmetics, polymer processing, and industrial mixing. Understanding viskoosne and viscosity helps predict flow, heat transfer, and mechanical performance in engineering and everyday contexts.