DEFINITION OF VISCOSITY

This question is usually best answered by example. Please imagine the hole in the bottom of the styrofoam cup. Then, if I poured the honey into the cup, I can see the cup draining slowly. This is because the viscosity of honey is higher than the viscosity of other liquids. For example, if you put water in the same cup, the cup will drain more quickly.

Viscosity is a measure of resistance to fluid flow. It represents internal friction of moving fluid. Fluids with large viscosities resist movement because their molecular composition gives them a lot of internal friction. Fluid with low viscosity flows easily because its molecular composition has very little friction during exercise.

The exact definition of viscosity is based on laminar flow or non-turbulent flow. Before defining the viscosity, it is necessary to define laminar flow and turbulence. Two types of processes are shown. Laminar flow is characterized by a smooth flow of fluid in an unmixed layer. Turbulence or turbulence is characterized by vortices and vortices that mix fluid layers. The smoke rises steadily for a while and then begins to form vortices and vortices. Smooth flow is called laminar flow, and vortices and vortices represent turbulent flow. When you see the smoke (be careful not to smoke) you will notice when the smoke flows faster than when it is disturbed. This means that turbulence produces greater resistance to flow. (Credit: Creativity 103)

Where τ = F / A, ∂u / ∂y is the local shear rate. This expression is called Newton's viscosity law. It is defined by plane symmetric shear flow. This is a special case of general viscosity definition (see below) and can be expressed in the form without coordinates. The use of the Greek letter mu (μ) indicates that the viscosity is common not only for physicists but also for mechanical and chemical engineers. However, the Greek letter eta (η) is used by chemists, physicists and IUPAC. Viscosity is sometimes called shear viscosity. However, at least one author does not recommend using this term and points out that it may appear in non-shear flow in addition to shear flow.

The fluid flowing through the stationary surface undergoes a force countering the flow. This tendency to resist flow is known as the viscosity of the fluid. Fluids such as air have low viscosity, thicker fluids like water are more viscous, fluids such as honey and oil are more viscous. Viscosity represents the internal flow resistance of a fluid and can be regarded as a measure of fluid friction. The higher the viscosity of the liquid, the slower the flow rate. Viscosity can be measured by calculating the time required for a given amount of liquid to flow through the capillary under gravity. The more viscous liquid, the more time it takes. The viscosity can also be determined by measuring the rate at which the steel ball falls into the liquid. As the viscosity increases, the sphere descends more slowly. Viscosity is related to the relative mobility of individual molecules of a liquid relative to each other.