Topics - Viscosity

Viscosity Fluids exhibit a definite resistance to change of form. This resistance to change represents a type of internal friction and is called viscosity. In practice the viscosity of a fluid usually manifests itself as a resistance to flow, both in liquids and gases but at a much lower level in gases. Viscosity is classically defined as the tangential force per unit area necessary to maintain unit relative velocity between two parallel plates in a liquid unit distance apart. The unit of viscosity is called the poise. Another form of viscosity measurement is the kinetic viscosity which is the ratio of the viscosity in poises to the fluid density in gram per ml. Kinetic viscosity is measured in stokes.