Viscosity
The Viscosity is a fluid property which measures the resistance of the fluid to distorting due to a shear force. The viscosity is an internal friction of a fluid that makes it resist flowing past a solid surface or other layers of the fluid. The viscosity can also be considered to be a measure of the resistance of a fluid to flowing. Thick oil has a very high viscosity; water has a low viscosity. The standard unit of measurement for absolute viscosity is:
µ = absolute viscosity of fluid (lbf-sec/ft2).
The viscosity of a fluid is generally appreciably reliant on the temperature of the fluid and associatively independent of the pressure. For most of the fluids, since the temperature of the fluid rises, the viscosity of the fluid reduces. An illustration of this can be view in the lubricating oil of engines. Whenever the engine and its lubricating oil are cold, the oil is much viscous, or thick. After the engine is happening and the lubricating oil rises in temperature, the viscosity of the oil reduces appreciably and the oil seems much thinner.