This document provides an introduction to fluid mechanics for a civil engineering course. It defines a fluid as a substance that continuously deforms under the application of shear stress, regardless of the magnitude of stress. Fluids are classified as liquids or gases depending on their molecular spacing. The document outlines the key differences between solids and fluids, noting that solids can resist shear stress while fluids deform continuously. It also introduces some fundamental fluid mechanics concepts like fluid statics, kinematics, and dynamics, which study fluids at rest, in motion without forces, and in motion with forces, respectively. The overall document serves as an introductory overview of fluid properties and the basic study of fluids.

1. SanjivaniRuralEducationSociety’s
SanjivaniCollegeof Engineering,Kopargaon,423603.
AnAutonomousInstituteAffiliatedtoSavitribaiPhulePuneUniversity,Pune
Subject:FluidMechanicsT.Y
.B.T
ech(CIVIL)
Unit-I:(A)FluidProperties
By
Prof.V.M.Mahajan(AssistantProfessor) DepartmentofCivil
Engineering
SanjivaniCollegeofEngineering,Kopargaon-423603

2. Contents
 Introduction to fluid mechanics,
 Scope and importance,
 Fluid as a continuum,
 Physical properties of fluids,
 Newton‘s law of viscosity,
 Classification of fluids,
 Rheological diagram.

3. IntroductiontoFluidMechanics
Accordingtothemolecularspacing,mattermaybeclassifiedas
1. Solids– molecularspacingisalmostzero
2. Fluids
a) Liquids–molecularspacingislargerthanSolids
b) Gases–molecularspacingislargerthanLiquids
WhatisFluid?
AFluidisasubstancethatdeformscontinuouslyinthefaceof tangentialor
shearstress,irrespectiveofthemagnitudeofshearstress.
Thiscontinuousdeformationundertheapplicationofshear stress.

4. Fluidmaybedefinedasasubstancewhichiscapableofflowing.
Ithasnodefiniteshapeofitsownbutoccupy/conformstotheshapeofthe containingvessel.
Further even small amount of shear force exerted on afluid will causeit to undergo a
deformationwhichcontinuesaslongasforcecontinuestoapply
Distinctionbetweenasolidandafluidismadeonthebasisofthesubstance’s abilitytoresistan
appliedshear(ortangential)stressthattendstochangeits shape.
Asolidcanresistanappliedshearstressbydeforming,whereasafluiddeforms
continuouslyundertheinfluenceofshearstress,nomatterhowsmall.
Insolidsstressisproportionaltostrain, butinfluidsstressisproportionalto strain rate. When
aconstantshearforceisapplied,asolideventuallystops deforming,atsomefixedstrainangle,
whereasafluidneverstopsdeformingand approachesacertainrateofstrain.
Whatis Fluid?

5. Whatis Fluid?
 Distinctionbetweensolidandfluid?
 Solid:canresistanappliedshearbydeforming.Stressisproportionalto strain
 Fluid:deformscontinuouslyunderappliedshear
.Stressisproportionalto strainrate

6. Fluid : - Tendency to flow
Ideal Fluids
(Viscosity,
Surface Tension
& it is
incompressible)
Real Fluids
(Viscosity, Surface
Tension and
possess
Compressibility)

7. Difference between Slid, Liquid andGas

8. Fluid Mechanics : - Branch of science that deals
with behaviour of fluid at rest as well as in
motion.
Fluid Statics
(Study of fluids
at rest)
Fluid
Kinematics
(Study of fluids
in motion
without
considering the
forces causing
the motion)
Fluid
Dynamics
(Study of fluids
in motion with
consideration of
the forces
causing the
motion)

9. IntroductiontoFluidMechanics

11. Thank You