What is viscosity


    • prajput
      Ansys Employee


      What is fluid viscosity?

      Thank you.

    • Keyur Kanade
      Ansys Employee

      Viscosity is the measure of the fluid resistance to deformation. When fluids move they tend to deform continuously. This is due to some internal forces (or better stresses) that we can call shear stresses. For some fluids, the deformation is proportional to the magnitude of the shear stresses. These fluids are known as 'Newtonian Fluids'. The SI units of viscosity are kg / (m s) or (Pa s).

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    • prajput
      Ansys Employee

      Thank you for the response! Why are there two types of viscosities? How do you differentiate between them?

      Thank you!

    • Keyur Kanade
      Ansys Employee

      Hi @prajput , the definition provided by my colleague is for the dynamic viscosity of the fluid. When you divide this number with the fluid density, you will obtain the kinematic viscosity.


      nu = mu / rho


      nu refers to kinematic viscosity,

      mu refers to dynamic viscosity, and

      rho refers to fluid density

      The SI unit is m^2/s.

      Thank you.?

    • bradl

      test teplay edited

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