When calculating the Reynolds number, dynamic viscosity is used in the denominator when the density of the fluid is known, while kinematic viscosity is utilized when it is more convenient to use. In the context of air flowing inside a pipe, the Reynolds number formula incorporates density in the numerator and dynamic viscosity in the denominator. Kinematic viscosity, defined as dynamic viscosity divided by density, can be calculated if both dynamic viscosity and density are available. Ultimately, the choice between dynamic and kinematic viscosity depends on the specific data at hand.
PREREQUISITESEngineers, fluid dynamics researchers, and students studying fluid mechanics who need to understand the application of viscosity in calculating Reynolds number.
The Reynolds number contains the density in the numerator and the dynamic viscosity in the denominator. The kinematic viscosity is equal to the dynamic viscosity divided by the density. So, if you know the dynamic viscosity and the density, you can calculate the kinematic viscosity. So, in practice, you use whichever is more convenient / available.PhyIsOhSoHard said:When calculating Reynolds number, when do I use dynamic viscosity and when do I use kinematic viscosity?
In a pipe with air flowing inside it, what would you use when calculating Reynolds number and why?