What is dynamic viscosity?

The dynamic viscosity of the fluid is defined as a shear tension divided by the speed gradient achieved when the shear force is applied to the liquid. The viscosity varies greatly between liquids. It is important in flow behavior of liquids.

The term used to describe fluid resistance to flow is viscosity. Syrup is more viscous than water; molasses more viscous than syrup. The viscosity is the result of the lightness with which the molecules slip around and are the function of chemistry, shape and temperature of molecules. Gases also have different viscosities. At the same temperature, oxygen is twice viscous as hydrogen or ammonia, while the viscosity of the nitrogen lies in the middle. The lower plate is stationary. The experimenter using a known force attempts to move the top plate around the bottom plate. In the film The Molecule Liquid Leads, the album has zero speed. The fluid molecules next to the top plate have the same speed as the top plate.

While fluid can be either gas or liquid, it is easier to think of liquids in this test. AfterKud the fabric separating the plate is water, the top plate slips very easily to the side. With melasa as a liquid, the top plate slowly moves with the same force.

The shear force is in the direction of force, unlike the tension or pressure forces, which in this case would be necessary to separate or approach the plates. The shear voltage is a shear force divided by a unit surface and is expressed as newtons per square meter (n/m

2

) or Pascals (PA). Viscosity calculations are usually performed in metric units.

Speed ​​gradient is the difference in the flow rate of the liquid next to the Thracy board E, which is zero, compared to the liquid next to the top plate, which is the same as the speed of the upper plate. Dynamic viscosity is then divided by shear speed and is measured in seconds Pascal (PA-S). Virtually viscosity is measured in Centipoise (CPO). One Centipoise equalsOne Millipascal the other.

Another measure of viscosity is kinematic viscosity. Kinematic viscosity is a dynamic viscosity divided by fluid density. Kinematic viscosity is easier to measure than dynamic viscosity, so it is often used to determine dynamic viscosity.

Newton fluid retains a constant dynamic viscosity independent of shear speed. The ketchup is a non -Jewton fluid. It has a high dynamic viscosity when the flow is low, but when flow increases, it becomes almost as liquid as water. This explains why people shake the ketchup bottles to speed up the flow of ketchup, but then end up too much on the plate.