17 March 2017

Viscosity to density

Density is deriving form viscosity. But one question in your mind How? Let us discuss that in this article.

We all know that viscosity and density are important properties of the fluid as well as in fluid mechanics. both are same but also some difference between viscosity and density are there. Viscosity is how well liquid stick to each other while density is a measurement of the molecular weight of the composition. 

There are two types of viscosity :
  1. Kinematic viscosity 
  2. Dynamic viscosity 
Kinematic viscosity measures the comparative rate at which a liquid or gas flows whereas dynamic viscosity measures a gas's or liquid's resistance to flow as force is applied to it.

For calculating density you must know both the kinematic and dynamic viscosity of a gas or liquid. 

Knowing just one of the values is not enough, because neither viscosity value has a direct enough mathematical relationship to density.

We can calculate the density of any liquid or gas if we know dynamic viscosity and kinematic viscosity by giving formula below.

Density = Dynamic viscosity / Kinematic viscosity

For example :

Consider a fluid with a dynamic viscosity of 10 Pascal seconds and a kinematic viscosity of 2 square meters per second, the equation would look like this :

Substituting value in above formula :
Density = 10 / 2

Perform the calculation and express the density in kilograms per cubic meter. you can get the answer that looks like this :

Density = 10 / 2 = 5 kilograms per cubic meter