Viskostitet

Viskostitet is often seen as a misspelling or variant of viskositet, the term used in several Nordic languages to denote viscosity. Viscosity is a property of fluids that describes their resistance to gradual deformation by shear or tensile stresses. In English, the standard term is viscosity; in Swedish, Norwegian, and Danish, viskositet is the common spelling, while viskostitet may appear in informal writing or as a misprint.

Dynamic viscosity, or absolute viscosity, measures a fluid’s internal resistance to shear and is expressed in pascal-seconds (Pa·s). Kinematic viscosity is the ratio of dynamic viscosity to density and has the unit square meters per second (m^2/s). Together these quantities express how a fluid flows under applied forces and how it responds to changes in temperature or pressure.

Viscosity depends strongly on temperature and, for many liquids, decreases as temperature rises. Water has a relatively low viscosity, while honey has a high viscosity. Fluids can be Newtonian, with constant viscosity independent of shear rate, or non-Newtonian, where viscosity varies with shear rate (for example, ketchup becomes less viscous when stirred or shaken).

Measurement methods include capillary viscometers, rotational viscometers, falling-ball viscometers, and rheometers. Viscosity is a critical parameter in engineering and industry, affecting pumping and piping energy requirements, lubrication, ink and coating formulations, food texture, and many other applications.