Viskoossuste

Viskoossuste is a term that describes the resistance of a fluid to flow. It is a fundamental property of liquids and gases that influences how easily they can be poured, pumped, or agitated. Imagine honey versus water; honey is much more viscous, meaning it flows more slowly. This difference in flow behavior is due to the internal friction within the fluid. In liquids, viscosity arises from the cohesive forces between molecules, which hinder their movement past each other. In gases, viscosity is primarily due to the momentum transfer between molecules as they collide.

The unit of dynamic viscosity is the Pascal-second (Pa·s) in the SI system, though the centipoise (cP) is also commonly used. Kinematic viscosity, which is dynamic viscosity divided by density, measures how readily a fluid flows under gravity. It is typically expressed in square meters per second (m²/s) or centistokes (cSt). Temperature plays a significant role in viscosity. For most liquids, viscosity decreases as temperature increases, as molecular motion overcomes cohesive forces more easily. Conversely, for gases, viscosity generally increases with temperature due to increased molecular collisions. Understanding viscosity is crucial in many fields, including engineering (e.g., fluid dynamics, lubrication), manufacturing, and even cooking.