Two layers of fluid which move close to each other generate a frictional force which is

proportional to :

  • their surface,
  • their relative velocity (one with respect to the other)

and inversely proportional to the distance which separates them.

detail of the integrated viscosity converter mecaflux

(detail of the integrated viscosity converter mecaflux)

Dynamic viscosity:

the proportionality factor that binds the surface, the velocity and the distance to the frictional force, is the coefficient of dynamic viscosity n. the legal unit of dynamic viscosity is the pascal second (pas-s) or Poiseuille (PI). This ratio varies depending on the temperature and the fluid.

kinematic viscosity:

if we divide the coefficient of dynamic viscosity by the density of the fluid, we obtain a ratio used in some formulas this report is named kinematic viscosity and its unit is m² / s. Designated also Stokes (St) or centistokes (cSt).1m²/s=10 000St=1 000 000cSt

in the tab "Major head loss" (pipes friction pressure losses) , an editor of fluid viscosity, allows you to choose a fluid and temperature, this choice determines the dynamic viscosity.

The editor of fluids allows you to set / save viscosity for a gas or liquid of your choice depending on the temperature and record it in the database Viscosity of your software. A database viscosities of fluids, gases or liquids, is incorporated into mecaflux with about 85 liquids and 35 gas , whose dynamic viscosity is given as a function of temperature. By selecting the temperature of the fluid of your choice, you refresh the dynamic viscosity, kinematic viscosity, temperature and density of your fluid , when calculating major head loss or minor head losses.

The editor of fluid viscosity:

dynamic kinematic viscosity

It is also possible to directly enter the dynamic viscosity that you want, when calculating major or minor head loss.

An interface named viscometer "home maid" allows you to evaluate the dynamic viscosity of a fluid with " basics utensils" (Menu Tools mecaflux)

viscosité dynamique cinematique fluides

the unit and its viscosity tab converter to convert the kinematic viscosity and dynamic viscosity

viscosity converter tab mecaflux