5/19/2023 0 Comments Kinematic viscosity equationThe unit of measure of kinematic viscosity is Centistokes (cSt).Ī basic difference between the dynamic and kinematic viscosity measurements is density. The time is converted directly to kinematic viscosity using a calibration constant provided for the specific tube. There are several ways to find the kinematic viscosity of a fluid, but the most common method is determining the time it takes a fluid to flow through a capillary tube. The unit of measure for dynamic viscosity is Centipoise (cP). The viscometer detects the variation in the viscosity of the sample as the speed, sometimes call shear rate, is changed. The rotational viscometer can adjust the turning speed of the probe as it moves in the liquid. For example, some of these liquids show an increase in viscosity with an increase in applied force while other non-Newtonian liquids decrease in viscosity with an increase in applied force. Non-Newtonian liquids change viscosity when exposed to different conditions. ![]() The rotational viscometer is particularly useful in measuring non-Newtonian liquids. Viscosity is determined by measuring the force - or torque - needed to turn the probe. These instruments rotate a probe in the liquid sample. Rotational viscometers are one of the more popular types of instruments used to measure dynamic viscosity. ![]() In the kinematic measuring method, gravity is the only force that acts on the sample. The mass (or weight) of a fluid is determined by gravity. Therefore, we say that steel has a greater density than ice cube. They may be the same size, but the steel cube weighs more than the ice cube. Think about an ice cube and a cube of steel. Need a Refresher on Density?ĭensity is the ratio of the mass (or weight) of the sample divided by the volume of the sample. Density is not a factor with dynamic viscosity. This is because kinematic results are dependent on the density of the fluid. To further complicate my attempt to simplify these concepts, two fluids that have the same dynamic viscosity can have different kinematic viscosities. Put another way, kinematic viscosity is the measure of a fluid’s inherent resistance to flow when no external force, except gravity, is acting on it. The other way is to measure the resistive flow of a fluid under the weight of gravity. One way is to measure a fluid’s resistance to flow when an external force is applied. This is my attempt to bring clarity to these two principal concepts. ![]() It's not easy to find a lot of information on the differences between dynamic and kinematic viscosity. When people talk about viscosity, they are talking about one of two things: kinematic viscosity or dynamic viscosity. These terms are derived from how the viscosity is measured. In reality, there are several different terms that come under the heading of viscosity. It helps describe how thick a product is, or how well it flows. At first glance, viscosity seems like a fairly simple concept.
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