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Mechanical Engineering vocabulary · Fluid Mechanics, Pumps and Valves

Viscosity

Meaning in mechanical engineering, with examples

/vɪˈskɑːsəti/nounCommon term

In mechanical engineering, viscosity means: A measure of how thick a fluid is and how strongly it resists flowing. Honey has a high viscosity and water has a low one.

In Turkish: viskozite, akmazlık

How it is used

Used for oils, hydraulic fluids and lubricants and in pump and pipe calculations. Viscosity falls as temperature rises. Oils are specified by viscosity grade, such as ISO VG 46. Dynamic viscosity is given in Pa·s and kinematic viscosity in mm²/s (cSt).

Example sentences

  1. In winter the oil viscosity is too high, and the hydraulic system responds slowly until it warms up.

  2. Use an oil with a viscosity grade of ISO VG 68 for this gearbox.

Common collocations

  • oil viscosity
  • viscosity grade
  • kinematic viscosity
  • dynamic viscosity
  • low viscosity
  • lubricationPutting oil or grease between moving surfaces, for example in bearings, gears and chains, to reduce friction, wear and heat.
  • flow rateThe amount of fluid that passes a point in a given time, given as a volume (for example m³/h or L/min) or as a mass (kg/s).
  • pressure dropThe loss of pressure as a fluid flows through a pipe, filter, valve or other component, caused by friction and by changes in direction or cross-section.
  • turbulent flowFluid flow in which the particles move in irregular, mixing paths. It happens at higher speeds and is the opposite of smooth, layered laminar flow.

This word in other fields

The same English word can have a different meaning in another field:

More terms: Fluid Mechanics, Pumps and Valves

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