Wiskoz

Wiskoz, often referred to as viscosity, is a physical property of fluids that describes their resistance to deformation and flow. It arises from internal friction between layers of fluid as they move past one another. In practical terms, liquids with high wiskoz flow more slowly than those with low wiskoz.

The dynamic viscosity (mu) quantifies this resistance. It is measured in pascal-seconds (Pa·s) in SI units, with centipoise (cP) commonly used in industry (1 cP = 0.01 Pa·s).

Kinematic viscosity (nu) combines viscosity and density: nu = mu / rho, with units of square meters per second (m^2/s).

Methods to measure wiskoz include capillary viscometers, such as Ubbelohde and Oswald, and rotational rheometers, which determine viscosity under different shear rates.

For Newtonian fluids, wiskoz is constant at a given temperature and pressure, independent of shear rate. Non-Newtonian fluids exhibit shear-rate dependent wiskoz; examples include shear-thinning (pseudoplastic) and shear-thickening (dilatant) liquids, as well as Bingham plastics that require a yield stress to flow.

Viscosity depends strongly on temperature and composition; typically, viscosity decreases with rising temperature and increases with higher molecular weight or presence of dissolved solutes. Temperature dependence is often described by Arrhenius-type or Andrade equations.

Applications span lubrication, hydraulic fluids, polymer processing, food and pharmaceutical industries, where controlling wiskoz is essential for performance and safety.