**Types of Fluid**

Topics Discussed:

**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-**

**Time-Dependent**

- Thixotropic Fluids
- Rheopectic Fluids

**Time-Independent**

- 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 (k**_{T}), Adiabatic Bulk Modulus

_{T}), 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.

**Compressibility (β)**

**What is Compressibility?**

- It is the inverse of Bulk Modulus of Elasticity.

β = 1/k = -dv/(v × dp)

v = volume

**Isothermal Bulk Modulus (k**_{T})

_{T})

**What is Isothermal Bulk Modulus?**

k_{T} = P_{final} = Ρrt

**Adiabatic Bulk Modulus**

**What is Adiabatic Bulk Modulus?**

k_{a} = ϒ × P_{final}

ϒ = C_{p}/C_{v}

I hope you enjoyed these Non-Newtonian Fluids and its types of Short Notes. Please do share with your **Mechanical Engineering friends.**

Thixotropic and Rheopectic fluids are time-dependent.

Thank you for pointing out the typo error.