![]() The viscosity of water decreases smoothly from the freezing point while the density remains essentially constant except for the small maximum in density near 4☌. In cgs units the unit is called the centistoke. The symbol for kinematic viscosity is nu: and its SI units are m/s 2. The kinematic viscosity is the dynamic viscosity divided by the density of the fluid. What is Kinematic Viscosity Kinematic viscosity is the ratio of absolute (dynamic) viscosity () see the previous sections - to density () and is a measure of a fluid’s inherent resistance to flow when no external force, except gravity, is acting on it. ![]() The unit centiPoise = 0.001 Pa s and is is sometimes written mPa s. One way is to measure a fluid’s resistance to flow when an external force is applied. Water at 20 ☌ has a kinematic viscosity of about 1 cSt. 1 cSt (centiStoke) 1 mm 2 /s 10 6 m 2 /s. Other units are: 1 St (Stoke) 1 cm 2 /s 10 4 m 2 /s. ![]() These viscosities are at 20☌ except for the blood and blood plasma which are at body temperature, 37☌, and for steam which is at 100☌. The SI unit of the kinematic viscosity is m 2 /s. The Poise is used in the table because of its more common usage. More commonly used is the dyne sec/cm 2 which is called Poise. It is surprising, therefore, that the variation, the decay rate of the velocity, has not been utilized for measuring (kinematic) viscosity of fluids. (Mass density is the mass of a substance divided by its volume.) The dimensions of kinematic viscosity are area divided by time the appropriate units are metre squared per second. The symbol for absolute (dynamic) viscosity is mu: µ (although eta is also sometimes used). Also in common use is Poise (P) although this is often quoted as cP (centiPoise). We know empirically the larger the stickiness, viscosity, of the fluid, more rapidly its velocity slows down. Kinematic viscosity is the absolute viscosity of a fluid divided by its mass density. The SI unit for absolute (dynamic) viscosity is Ns/m 2 (or 1Kg/ms). Viscosity has the SI units Pascal seconds (Pa s) which is called the Poiseuille. On a daily basis we stir tee or coffee with a spoon and leave it to rest. Viscosity of Liquids and Gases Viscosity of Liquids and Gases Liquids
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |