ATMIYA institute of technology & science

NAME :- BHARGAV SHOLANKI - 150030106106 BHAUTIK VACHHANI - 150030106114 HEMAL VADHER - 150030106115

BRANCH:- CIVIL ENGNEERING

DIVISON:- GY-3

SUBJECT:- FLUID MECHANICS

FLUID & THIER PROPERTIES

INTRODUCTION

Definition of Fluid :- All matter can be divided into 2 major classes

1) Solid 2) Fluids

The difference between a solid and fluid can be defined by

1) The stress-strain relationship

2) The elasticity

Solid

requires external forces to cause it to deform.

Fluid will deform without the

application of external forces.

will take on the shape of the container in which they are held.

-Ex. water, oil, gas etc.

Hydrostatics: that studies the mechanics of fluids at absolute and relative rest.

Kinematics: deals with translation, rotation and deformation of fluid without considering the force and energy causing such a motion.Dynamics: that prescribes the relation between velocities and acceleration and the forces which are exerted by or upon the moving fluids.

Fluid machanics

Properties of Fluids

Density is the mass of the fluid per unit volume

Density ()

= Density of fluid, kg/m3

M = Mass of fluid, kgV = Unit volume, m3

= MV

The specific weight is the weight of the fluid per unit volume

= Specific weight, N/m3

W = Weight of fluid, N (W=mg)V = Unit volume, m3

= WV

The specific weight of water at 40C = 9.81 kN/m3

Specific Weight/Unit Weight ()

The specific gravity is the ratio of the density or specific weight of the fluid to the density or specific weight of water, at a temperature of 4oC

Specific Gravity/Relative Gravity (S)

S =w =

w Dimensionless

Viscosity It is the property of the fluid by virue of which it offers resistance to shear or angular deformation.

Mollases,tar, glycerine are highly viscous fluids.

Water,air,petrol have very small viscosity and are called thin fluids.

Newton’s Law of Viscosity

= (du/dy)

Where, du/dy =velocity gradient

= coefficient of viscosity.

It’s states that the shear stress( ) on a fliud element layer is directly proportional to the rate of shear strian.

Classifiction of fluid

The fluid may be classified into the five types:-

1) Ideal fluid 2) Real fluid 3) Newtonian fluid 4) Non – newtonian fluid 5) Ideal plastic fluid

Ideal fluid is a substance that is unable to resist internal shear

and tensile forces.

Real fluid :- A fluid which is compressible , has visocity and surface tension ,is known as real fluid

Newtonian fluid:- A real fluid in which the shear stress is directly to the rate of shear strain ,is known as newtonian fluid.

Non-newtonian fluid:-A real fluid , in which the shear stress is not proportional to the rate of shear strain,is known as non- newtonian fluid.

Ideal plastic fluid:- a fluid in which shear stress is more than the yield value and shear stress is proportional to the rate of shear strain is known as an ideal plastic fluid.

surface tension Tensile force acting on

the free surface of aliquid per unit length is called surface tension

s.I unit of surface tension is N/M or N/MM it is denoted by sigma (σ)

Surface tension is a contractive tendency of the surface of a fluid that allows it to resist an external force. Surface tension is an important property that markebly influences the ecosystems.

CAPILLARY

Capillary action is the ability of a fluid to flow in narrow spaces without the assistance of, and in opposition to, external forces like gravity.

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