Fluid Mechanics For Chemical EngineeringPresentation 1

Topic: Introduction to Fluid Mechanics

COMSATS LAHORE

Sequence of Presentation

Introduction to Fluid Mechanics• Aneel Ahmad

Basic Principles of Fluid Mechanics• Ahmad Nawaz

Instrumentation of Fluid Mechanics• Tamoor Tariq

Applications of Fluid Mechanics• M. Rizwan

Objectives

Fluid mechanics deals with the study of all fluids under static and dynamic situations.

Fluid mechanics is a branch of continuous mechanics which deals with a relationship between forces, motions, and static conditions in a continuous material.

Major problems it dealt with are:•Surface Tension•Fluid Statics•Flow in enclosed bodies•Flow round bodies•Flow stability…..etc.

What is Fluid Mechanics?

Fluid Concept

Anything which can flow or which do not show permanent friction over any surface.Types of Fluid:• Compressible Fluid

ρ=0

• Non-compressible Fluidρ≠0

Fluid Newton’s lawof viscosity

Newtonian fluids obey refer

Example:AirWaterOilGasolineAlcoholKeroseneBenzeneGlycerine

Fluid

Newton’s lawof viscosity

Non- Newtonianfluids

Do not obey refer

Ketchup, shampoo, blood, paint etc

Newtonian and Non-Newtonian Fluids

= . du/dy

Flow Patterns

Laminar Flow

Turbulent FlowTransitional

Flow

Flow Patterns

Bernoulli’s PrincipleIn fluid dynamics, Bernoulli's principle states

that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure.

Continuity Equation In fluid mechanics, the continuity equation states that, In any steady

state process, the rate at which mass enters a system is equal to the rate at which mass leaves the system.

The differential form of the continuity equation is:

Where, ρ is fluid density, t is time, u is the flow velocity vector field. If ρ is a constant, as in the case of incompressible fluid, the mass

continuity equation simplifies to a volume continuity equation:

Reynolds Number

In fluid mechanics, the Reynolds number (Re) is a dimensionless number that gives a measure of the ratio of inertial forces to viscous forces and consequently quantifies the relative importance of these two types of forces for given flow conditions.

Re= duρ/ μ

The flow is• laminar when Re < 2100• transition phase when 2100 < Re < 4000• turbulent when 4000 < Re