GPa s(gigapascal second)

In the field of fluid dynamics, dynamic viscosity is a measure of a fluid's resistance to flow, which quantifies its internal friction. It is the property that determines how easily a fluid can be deformed or moved under an applied force. It is denoted by the Greek letter 'η' (eta) and is usually measured in units of Pascal-seconds (Pa·s).

A gigapascal second (GPa s) is a unit used for expressing very high dynamic viscosities, particularly when dealing with materials that have extremely high internal resistance to flow, such as some polymers, metals, or very high-pressure systems. The unit GPa s can be understood as the viscous force exerted by the material when a pressure of 1 gigapascal (1 billion pascals or 1 GPa) is applied to it for 1 second. Thus, 1 GPa s is equivalent to 1 billion Pascal-seconds (1 x 10⁹ Pa·s).

GPa s is not commonly used for most fluids like gases and liquids, as their dynamic viscosities are usually much lower and can be represented in smaller units such as Pa·s or centipoise (cP). However, GPa s can be useful when evaluating the rheological properties of materials that exhibit exceptionally high viscous behavior.

µPa s(micropascal second)

A micropascal second (µPa·s) is a unit of dynamic viscosity in the International System of Units (SI). Dynamic viscosity is a measure of a fluid's resistance to flow or, in simpler terms, its internal friction. When a force is applied to a fluid, the layers of the fluid will move against each other, and the dynamic viscosity represents the resistance between these layers.

In the field of dynamic viscosity, a micropascal second is a very small unit of measurement. It can be represented as:

1 µPa·s = 1 x 10^-6 Pa·s

where 1 Pa·s (pascal second) is the SI unit of dynamic viscosity. A micropascal second is used for measuring the viscosity of very low viscous fluids or gases, like air or other light gases.

To provide some more context, liquids like water or oil have higher viscosities (measured in millipascal seconds, mPa·s), while substances like honey or molasses have even higher viscosities (measured in pascal seconds, Pa·s).