Types of Fluid
What is Fluid?
A Fluid is a substance that has a tendency to flow. Example – Gases and Liquids
These fluids can be classified into two categories.
- Newtonian Fluid
- Non-Newtonian Fluid
Non- Newtonian Fluids
What are Non-Newtonian Fluids?
Non-Newtonian Fluids are the types of fluids that do not obey Newton’s Law of viscosity. The relation between Shear Stress and Velocity gradient is given by the following formula-
τ = A (du/dy)n + B
Here A and B are constants that depend on the type of fluid and condition of flow.
Non- Newtonian Fluids Types
The Non-Newtonian Fluids are further categorized as-
- Thixotropic Fluids
- Rheopectic Fluids
- Dilatant Fluids
- Bingham Plastic Fluids
- Pseudo plastic Fluids
Non-Newtonian Fluids Conditions
For Dilatant Fluids
- n > 1; and B = 0
- Ex- Butter, Quicksand
For Bingham Plastic Fluids
- n = 1; and B ≠ 0
- These fluids always have certain minimum shear stress before yielding.
- Ex- toothpaste, gel, sewage sludge, etc.
For Pseudoplastic Fluids
- n < 1 ; and B = 0
- Ex- Paints, Blood, Paper pulp, Lipsticks, Rubber solution etc.
For Thixotropic Fluids
- n < 1; and B ≠ 0
- Viscosity increases with time.
- Ex- Enamel, Printers Ink, etc.
For Rheopectic Fluids
- Viscosity decreases with time.
- Ex- Gypsum solution in water, etc.
Compressibility (β), Isothermal Bulk Modulus (kT), Adiabatic Bulk Modulus
Let us first understand about Bulk Modulus (K).
The Bulk Modulus (K) of any substance is basically the amount of resistance it can withstand on compression.
What is Compressibility?
- It is the inverse of Bulk Modulus of Elasticity.
β = 1/k = -dv/(v × dp)
v = volume
Isothermal Bulk Modulus (kT)
What is Isothermal Bulk Modulus?
kT = Pfinal = Ρrt
Adiabatic Bulk Modulus
What is Adiabatic Bulk Modulus?
ka = ϒ × Pfinal
ϒ = Cp/Cv
I hope you enjoyed these Non-Newtonian Fluids and its types of Short Notes. Please do share with your Mechanical Engineering friends.