This post centers around the **Fluid Dynamics Class Notes for class 11** (includes viscosity) for boards like ISC, CBSE, IGCSE, etc. A fluid is a collection of molecules that are randomly arranged and held together by weak cohesive forces and by forces exerted by the walls of a container. Both liquids and gases are fluids. The mechanics of fluids in motion is known as *fluid dynamics.*

**Flow Characteristics** – basic understanding

When fluid is in motion, its flow can be characterized as being one of two main types. The flow is said to be steady, or laminar if each particle of the fluid follows a smooth path, such that the paths of different particles never cross each other. In steady flow, the velocity of the fluid at any point remains constant in time.

Above a certain critical speed, the fluid flow becomes turbulent; turbulent flow is irregular flow characterized by small whirlpool-like regions, (Hot gases from a cigarette made visible by smoke particles. The smoke first moves in laminar flow at the bottom and then in the turbulent flow above.).

The term viscosity is commonly used in the description of fluid flow to characterize the degree of internal friction in the fluid. This internal friction, or *viscous* *force, *is associated with the resistance that two adjacent layers of fluid have to move relative to each other. Viscosity causes part of the kinetic energy of a fluid to be converted to internal energy. This mechanism is similar to the one by which an object sliding on a rough horizontal surface loses kinetic energy.

**Fluid Dynamics Class Notes for class 11 (includes viscosity)**

We have detailed posts (tutorials) covering different important topics under the Fluid Dynamics chapter. We are including the links to the major ones in the following paragraph. You may go through these to get a good grasp of the chapter.

**Viscosity – definition, derivation, coefficient of viscosity**

**How to derive Terminal Velocity equation using Stokes’ law (step by step)**

**Numerical problem on Terminal Velocity with solution**

**Reynolds number, significance, formula, sample numerical**

**The Equation of Continuity with derivation & Streamlines of fluid flow**

**Bernoulli’s equation with derivation & explanation**

**What Is Bernoulli’s Principle? Explain it with airplane wing and sails example**

**Fluid flow – important formulas**