Viscosity
of fluids
By Alanoud Maskin
What is viscosity?
its a measure of internal, frictional resistance to flow. Viscosity is also inversely proportional to
density. μ=1/ρ
Types of fluids
There are two types of fluids covered in class, Newtonian fluids and non-newtonian fluids, nonnewtonian fluids are divided into three parts, Pseudoplastic, Bingham plastic, and Dilatant.
Newtonian Fluids
Newtonian fluids are fluids whose deformation rate is
proportional to the shear stress applied, and the
constant proportionality is considered viscosity, for
example, air, water, and oil.
Non-Newtonian
Fluids
Non-Newtonian fluids are fluids that do not obey Newton fluid law
and they’re divided into three types:
pseudoplastic: shear-thinning fluids and viscosity decrease with
increasing shear stress such example blood and latex paint.
Dilatant fluid: shear thinking fluid and its viscosity increases with
increasing shear rate such as cornstarch solution.
Bingham plastic: it’s neither a fluid nor a solid and it can
withstand finite stress without motion but when yield stress is
exceeded it flows like a fluid such as toothpaste and ketchup.
Newtonian fluid
Water
• Viscosity remains constant
no matter shear stress
applied
• Deformation rate is
proportional to shear stress
rate
• Gasoline, air, water
Non-Newtonian fluid
Dilatant fluid
• Shear Thickening
• Viscosity increase with
shear rate increase
• Cornstarch Solution
Bingham plastic
• Neither a solid or a fluid at
static and when yield stress
is exceeded then it will act
like a fluid
• Viscosity increase with
shear rate increase
• Ketchup and toothpaste.
References
1. George, H.F., Qureshi, F. (2013). Newton’s Law of Viscosity, Newtonian and Non-Newtonian Fluids. In:
Wang, Q.J., Chung, YW. (eds) Encyclopedia of Tribology. Springer, Boston, MA.
https://doi.org/10.1007/978-0-387-92897-5_143
2. Nevers, N. D. (2020). Fluid Mechanics for Chemical Engineers (4th ed.). McGraw-Hill Higher Education
(US). https://reader2.yuzu.com/books/9781260587418