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SURVEY ON FLUIDS AND PROPERTIES

NAWFEL MUHAMMED BAQER

M. Sc, Department of Mechanical Engineering, Technical College, Iraq

ABSTRACT

This review study involves different types of fluids, their properties, their effects, causes of viscosity in tubes.

Flow conditioning makes a huge effect on the accuracy of liquid turbine meter which results into flow disturbances. These

effects are mainly caused by debris on strainer screens, for various upstream piping geometries and different types of flow

conditioners.

KEYWORDS : Frame, Drop, Parameter, Geometry

INTRODUCTION

Fluids can be classified into four basic types. They are

• Ideal Fluid

• Real Fluid

• Newtonian Fluid

• Non-Newtonian Fluid

• Ideal Fluid

An Ideal Fluid is a fluid that has no viscosity. It is incompressible in nature. Practically, no ideal fluid exists.

• Real Fluid

Real fluids are compressible in nature. They have some viscosity.

Examples: Kerosene, Petrol, Castor oil

• Newtonian Fluid

Fluids that obey Newton’s law of viscosity are known as Newtonian Fluids. For a Newtonian fluid, viscosity is

entirely dependent upon the temperature and pressure of the fluid.

Examples: water, air, emulsions

• Non-Newtonian Fluid:

Fluids that do not obey Newton’s law of viscosity are non-Newtonian fluids.

Examples: Flubber, Oobleck (suspension of starch in water)

Properties of fluids determine how fluids can be used in engineering and technology. They also in the behaviour

of fluids in fluid mechanics. The following are some of the important basic properties of fluids:

TJPRC:International Journal of Fluid Mechanics & Acoustical Engineering (TJPRC:IJFMAE) Vol. 1, Issue 1, Jun 2015, 7-14 © TJPRC Pvt. Ltd

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• Density

• Viscosity

• Temperature

• Pressure

• Specific Volume

• Specific Weight

• Specific Gravity

• Density:

Density is the mass per unit volume of a fluid. In other words, it is the ratio between mass (m) and volume (V) of

a fluid.

Density is denoted by the symbol ‘ρ’. Its unit is kg/m3.

In general, density of a fluid decreases with increase in temperature. It increases with increase in pressure.

Note: The density of standard liquid (water) is 1000 kg/m3.

• Viscosity

Viscosity is the fluid property that determines the amount of resistance of the fluid to shear stress. It is the

property of the fluid due to which the fluid offers resistance to flow of one layer of the fluid over another adjacent layer.

In a liquid, viscosity decreases with increase in temperature. In a gas, viscosity increases with increase in temperature.

• Temperature:

It is the property that determines the degree of hotness or coldness or the level of heat intensity of a fluid.

Temperature is measured by using temperature scales.There are 3 commonly used temperature scales. They are

• Celsius (or centigrade) scale

• Fahrenheit scale

• Kelvin scale (or absolute temperature scale)

Kelvin scale is widely used in engineering. This is because, this scale is independent of properties of a substance.

• Pressure

Pressure of a fluid is the force per unit area of the fluid. In other words, it is the ratio of force on a fluid to the area

of the fluid held perpendicular to the direction of the force.

Pressure is denoted by the letter ‘P’. Its unit is N/m2.

• Specific Volume:

Specific volume is the volume of a fluid (V) occupied per unit mass (m). It is the reciprocal of density.

Survey on Fluids and Properties

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Specific volume is denoted by the symbol ‘v’. Its unit is m

• Specific Weight

Specific weight is the weight possessed by unit volume of a fluid. It is denoted by ‘w’. Its unit is N/m

Specific weight varies from place to place due to the change of acceleration due to gravity (g).

• Specific Gravity

Specific gravity is the ratio of specific weight of the

denoted by the letter ‘S’. It has no unit.

Specific gravity may also be defined as the ratio between density of the given fluid to the density of standard

fluid.

Types of Fluid Flow

Based on flow characteristics, fluid flow can be broadly classified into two types:

• Laminar Flow

• Turbulent Flow

Laminar Flow

A fluid flow is said to be laminar, if each particle of the fluid follows the path of its preceding particle.

In laminar flow, individual fluid particles do not cross each other. They move in regular paths in an orderly

manner.

The fluid particles move smoothly in layers (laminae), one over the other.

A good example of laminar flow is the flow of blood through the arteries and veins of the h

example is the flow of oil through a thin tube.

Turbulent Flow

In turbulent flow, fluid particles move in a zig

Specific volume is denoted by the symbol ‘v’. Its unit is m3/kg.

weight possessed by unit volume of a fluid. It is denoted by ‘w’. Its unit is N/m

Specific weight varies from place to place due to the change of acceleration due to gravity (g).

Specific gravity is the ratio of specific weight of the given fluid to the specific weight of standard fluid. It is

Specific gravity may also be defined as the ratio between density of the given fluid to the density of standard

low characteristics, fluid flow can be broadly classified into two types:

A fluid flow is said to be laminar, if each particle of the fluid follows the path of its preceding particle.

fluid particles do not cross each other. They move in regular paths in an orderly

The fluid particles move smoothly in layers (laminae), one over the other.

A good example of laminar flow is the flow of blood through the arteries and veins of the h

example is the flow of oil through a thin tube.

In turbulent flow, fluid particles move in a zig-zag and haphazard way. They do not follow any regular pattern

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weight possessed by unit volume of a fluid. It is denoted by ‘w’. Its unit is N/m3.

Specific weight varies from place to place due to the change of acceleration due to gravity (g).

given fluid to the specific weight of standard fluid. It is

Specific gravity may also be defined as the ratio between density of the given fluid to the density of standard

A fluid flow is said to be laminar, if each particle of the fluid follows the path of its preceding particle.

fluid particles do not cross each other. They move in regular paths in an orderly

A good example of laminar flow is the flow of blood through the arteries and veins of the human body. Another

zag and haphazard way. They do not follow any regular pattern

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while flowing.

Individual fluid particles cross one another and

A good example of turbulent flow is the flow of river water. River water does not follow any regular flow pattern.

It moves in a zig-zag and haphazard manner.

Reynolds Number

Reynolds number (denoted by ‘Re’) is a dimensio

laminar or turbulent. Reynold’s number is given by the following equation:

Where,

ρ → Density of the fluid in kg/m

u → Mean Velocity of the fluid in m/s

D → Diameter of the pipe

μ → Dynamic viscosity of the fluid in Ns/m

ν → Kinematic viscosity of the fluid in m

Determination of flow regime using Reynolds Number:

Reynolds number (Re) can be used to find the

• If Re < 2300, the fluid flow is said to be laminar

• If Re > 4000, the fluid flow is turbulent

• If 2300 < Re < 4000, the fluid flow is unstable i.e., the flow may become either laminar or turbulent.

A non-Newtonian fluid is a fluid

commonly, the viscosity(the measure of a fluid's ab

Newtonian fluids is dependent on shear rate

viscosity, however, still exhibit normal stress

molten polymers are non-Newtonian fluids, as are many commonly found substan

starch suspensions, paint, blood, and shampoo

rate is linear, passing through the origin

Newtonian fluid, the relation between the

Dependent Viscosity). Therefore, a constant coefficient of viscosity cannot be def

Although the concept of viscosity is commonly used in

fluid, it can be inadequate to describe non

Individual fluid particles cross one another and exhibit irregular energy losses.

A good example of turbulent flow is the flow of river water. River water does not follow any regular flow pattern.

zag and haphazard manner.

Reynolds number (denoted by ‘Re’) is a dimensionless number used to determine whether the flow of a fluid is

laminar or turbulent. Reynold’s number is given by the following equation:

Density of the fluid in kg/m3

Mean Velocity of the fluid in m/s

viscosity of the fluid in Ns/m2

Kinematic viscosity of the fluid in m2/s

Determination of flow regime using Reynolds Number:

Reynolds number (Re) can be used to find the type of flow of a fluid

luid flow is said to be laminar

00, the fluid flow is turbulent

If 2300 < Re < 4000, the fluid flow is unstable i.e., the flow may become either laminar or turbulent.

fluid with properties that differ in any way from those of

(the measure of a fluid's ability to resist gradual deformation by shear or tensile stresses) of non

shear rate or shear rate history. Some non-Newtonian fluids with shear

viscosity, however, still exhibit normal stress-differences or other non-Newtonian behavior. Many

Newtonian fluids, as are many commonly found substances such as

shampoo. In a Newtonian fluid, the relation between the

origin, the constant of proportionality being the coefficient of

Newtonian fluid, the relation between the shear stress and the shear rate is different and can even be time

). Therefore, a constant coefficient of viscosity cannot be defined.

Although the concept of viscosity is commonly used in fluid mechanics to characterize the

fluid, it can be inadequate to describe non-Newtonian fluids. They are best studied through several

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A good example of turbulent flow is the flow of river water. River water does not follow any regular flow pattern.

nless number used to determine whether the flow of a fluid is

If 2300 < Re < 4000, the fluid flow is unstable i.e., the flow may become either laminar or turbulent.

differ in any way from those of Newtonian fluids. Most

ility to resist gradual deformation by shear or tensile stresses) of non-

Newtonian fluids with shear-independent

Newtonian behavior. Many salt solutions and

ces such as ketchup, custard, toothpaste,

. In a Newtonian fluid, the relation between the shear stress and the shear

, the constant of proportionality being the coefficient of viscosity. In a non-

is different and can even be time-dependent (Time

to characterize the shear properties of a

Newtonian fluids. They are best studied through several

Survey on Fluids and Properties 11

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other rheological properties that relate stressand strain rate tensors under many different flow conditions—such

as oscillatory shear or extensional flow—which are measured using different devices or rheometers. The properties are

better studied using tensor-valued constitutive equations, which are common in the field of continuum mechanics.

Table 1

Comparison of Non-Newtonian, Newtonian, and Viscoelastic Properties

Viscoelastic

Kelvin material,Maxwell material

"Parallel" linearstic combination of elastic and viscous effects[1]

Some lubricants, whipped cream, Silly Putty

Time Dependent Viscosity

Rheopecty

Apparent viscosity increases with duration of stress

printer ink, gypsum paste

Thixotropic

Apparent viscositydecreases with duration of stress[1]

Yogurt, xanthan gum solutions, aqueous iron oxide gels, gelatin gels, pectin gels,synovial fluid, hydrogenated castor oil, some clays (including bentonite, andmontmorillonite), carbon black suspension in molten tire rubber, some drilling muds, many paints, many floc suspensions, many colloidal suspensions

Time-independent viscosity

Shear thickening(dilatant)

Apparent viscosityincreases with increased stress[2]

Suspensions of corn starch in water, sand in water

Shear thinning(pseudoplastic)

Apparent viscositydecreases with increased stress[3][4]

Nail polish, whipped cream, ketchup, molasses, syrups, paper pulp in water, latex paint, ice, blood, some silicone oils, some silicone coatings

Generalized Newtonian fluids

Viscosity is constant. Stress depends on normal and shear strain rates and also the pressure applied on it

Blood plasma, custard, water

In physics, fluid dynamics is a sub discipline of fluid mechanics that deals with fluid flow the natural science of

fluids (liquids and gases) in motion. It has several sub disciplines itself, including aerodynamics (the study of air and other

gases in motion) and hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications,

including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines,

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predicting weather patterns, understanding nebulae in interstellar space and modeling fission weapon detonation. Some of

its principles are even used in traffic engineering, where traffic is treated as a continuous fluid, and crowd dynamics.

Fluid dynamics offers a systematic structure—which underlies these practical disciplines—that embraces

empirical and semi-empirical laws derived from flow measurement and used to solve practical problems. The solution to a

fluid dynamics problem typically involves calculating various properties of the fluid, such as flow

velocity, pressure, density, and temperature, as functions of space and time.

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