14. ASSIGNMENT TOPICS WITH...

G.MOUNIKA NAIDU, ASST PROFESSOR

14. ASSIGNMENT TOPICS WITH MATERIALS UNIT 1

1. Physical properties of fluids

2. Pascal’s law and hydrostatic law

3. Hydrostatic forces on submerged plane

4. Measurement of pressure

5. Manometers.

1. Physical properties of fluids

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

determine the behaviour of fluids in fluid mechanics. The following are some of the important

basic properties of fluids:

1. Density

2. Viscosity

3. Temperature

4. Pressure

5. Specific Volume

6. Specific Weight

7. Specific Gravity

1. 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.


The ideal gas equation is given by:

The above equation is used to find the density of any fluid, if the pressure (P) and temperature

(T) are known.

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

2. 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.

Viscosity – Animation Video

3. 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

1. Celsius (or centigrade) scale


2. Fahrenheit scale

3. 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.

4. 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.

5. Specific Volume:

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

density.

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

6. Specific Weight:

Specific weight is the 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).

7. Specific Gravity:

Specific gravity is the ratio of specific weight of the given fluid to the specific weight of

standard fluid. It is 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.

2.

Pascal’s Law

This law states that the pressure at a point in a fluid at rest is the same in all directions. To show

this, we will consider a very small wedge of fluid surrounding the point.

This wedge is unit thickness into the page:

And so the pressure at a point is the same in any direction. We neglected the weight of the small

wedge of fluid because it is infinitesimally small. This is why Pascal’s Law is restricted to the

pressure at a point.

Hydrostatics Law

A Hydrostatics Law state that rate of increase of pressure in a vertically downward direction in

fluid/liquid is equal to weight density of the liquid.

3.


4.

Pressure measurement is the analysis of an applied force by a fluid (liquid or gas) on a

surface. Pressure is typically measured in units of force per unit of surface area. Many

techniques have been developed for the measurement of pressure and vacuum. Instruments used

to measure and display pressure in an integral unit are called pressure gauges or vacuum gauges.

A manometer is a good example as it uses a column of liquid to both measure and indicate

pressure. Likewise the widely used Bourdon gauge is a mechanical device which both measures

and indicates and is probably the best known type of gauge.

A vacuum gauge is a pressure gauge used to measure pressures lower than the ambient

atmospheric pressure, which is set as the zero point, in negative values (e.g.: -15 psi or -760

mmHg equals total vacuum). Most gauges measure pressure relative to atmospheric pressure as

the zero point, so this form of reading is simply referred to as "gauge pressure". However,

anything greater than total vacuum is technically a form of pressure. For very accurate readings,

especially at very low pressures, a gauge that uses total vacuum as the zero point may be used,

giving pressure readings in an absolute scale.


5.

Main characteristics of manometers are pressure range, accuracy, sensitivity and speed of

response. Pressure range of manometers varies from almost perfect vacuum to several hundreds

of atmosphere. The conventional instruments used for pressure measurement are divided into the

following groups.

1) Liquid column manometers

2) Pressure gauges with elastic sensing elements

3) Pressure transducers

4) Manometers for low absolute pressures

5) Manometers for very high absolute pressures

UNIT 2 1. Liquids in relative equilibrium

2. Description of fluid flow

3. Classification of flows

4. Equation of continuity

5. Flow net analysis

KEY

1.

Relative equilibrium of liquid is a condition where the whole mass of liquid including the vessel

in which the liquid is contained, is moving at uniform accelerated motion with respect to the

earth, but every particle of liquid have no relative motion between each other. There are two

cases of relative equilibrium linear translation and rotation.

2.

Consider a typical fluid element of certain volume at any arbitrary time as shown in Fig. 3.2.1.

After certain time interval, it has moved and changed its shape as well as orientation drastically.


However, when we limit our attention to an infinitesimal particle of volume at

time t and within the fluid element, it may be observed that the change of its shape is

limited to only stretching/shrinking and rotation with its sides remaining straight even though

there is a drastic change in the finite fluid element. Thus, the particle motion in a fluid flow can

be decomposed into four fundamental components i.e. translation, rotation, linear

strain and shear strain as shown in Fig. 3.2.2. When the fluid particle moves in space from one

point to another, it is referred as translation. Rotation of the fluid particle can occur in any of the

orthogonal axis. In the case of linear strain , the particle's side can stretch or shrink. When the

angle between the sides of the particle changes, it is called as shear strain.

3.

The flow of fluids can be classified according to various criteria of the fluid that flows.

According to geometrical criteria:

I. Direction of the flow

a) One dimensional flow

Flow in one direction. For example, Flow through pipes.

b) Two dimensional flow

Flow in two dimensional space. For example, air flow around airplane wing.

c) Three dimensional flow

Flow represented by three-dimensional space. For example flow through control volume.

II. Region of flow.

a) Internal flow

Flow considered inside a region. For example, Flow of refrigerant inside copper tube in

condenser.

b) External flow

Flow considered outside a region. For example, Flow of air over the copper tube in condenser.

According to kinematic criteria:

III. Position of fluid particles

a) Uniform fluid flow

Position of fluid particle at inlet and outlet of a fluid flow is constant.

b) Non uniform fluid flow

Position of fluid particles is altered with the fluid flow.


IV. Variation of parameters with time.

a) steady flow

Fluid parameters are independent of time

b) Unsteady flow

Fluid parameters are time dependent

V. Vorticity vector of the fluid particles

a) Irrotational flow

b) Rotational flow

VI. Velocity of the flow.

a) subsonic flow (Mach number M < 1)

b) Transonic flow (M = 1)

c) Supersonic flow (1 ≤ M ≤ 5)

d) Hypersonic flow (M > 5)

VII. Motion (path) of the fluid particles.

a) Laminar flow

Fluid particles follows streamline motion. Reynolds number Re < 4000

b) Turbulent flow

Fluid particles flow in random path. Reynolds number Re < 4000.

According to physical criteria:

VIII. Position of fluid particles

a) Incompressible flow (ρ=constant)

b) Compressible flow (ρ≠constant).

4.

A continuity equation in physics is an equation that describes the transport of some quantity. It

is particularly simple and powerful when applied to a conserved quantity, but it can be

generalized to apply to any extensive quantity. Since mass, energy, momentum, electric

charge and other natural quantities are conserved under their respective appropriate conditions, a

variety of physical phenomena may be described using continuity equations.

Continuity equations are a stronger, local form of conservation laws. For example, a weak

version of the law of conservation of energy states that energy can neither be created nor

destroyed—i.e., the total amount of energy is fixed. This statement does not immediately rule


out the possibility that energy could disappear from a field in Canada while simultaneously

appearing in a room in Indonesia.

5.

A flownet is a graphical representation of two-dimensional steady-state groundwater flow

through aquifers.

Construction of a flownet is often used for solving groundwater flow problems where the

geometry makes analytical solutions impractical. The method is often used in civil

engineering, hydrogeology or soil mechanics as a first check for problems of flow under

hydraulic structures like dams or sheet pile walls. As such, a grid obtained by drawing a series of

equi-potential lines is called a flow net. The flownet is an important tool in analysing two-

dimensional ir-rotational flow problems. Flow net technique is a graphical representation

method.

UNIT 3 1. Eulers equation

2. Bernoullis equation

3. Pitot tube

4. Classification of orifices

5. Broad crested weirs

KEY

1.


2.


3.

Pitot tube is one of the simplest flow sensors; it is used in a wide range of flow measurement

applications such as air speed in racing cars and Air Force fighter jets. In industrial applications,

pitot tubes are used to measure air flow in pipes, ducts, and stacks, and liquid flow in pipes,

weirs, and open channels. While accuracy and range ability are relatively low, pitot tubes are

simple, reliable, inexpensive, and suited for a variety of environmental conditions, including

extremely high temperatures and a wide range of pressures.

4.

Classification of Orifices

Orifices are classified on the basis of many criteria such as:

1. Size

2. Shape

3. Nature of discharge

4. Nature of upstream edge etc.

These are explained briefly as below:

Classification based on shape: Orifices are classified into small orifice and large

orifice depending upon the size of orifice and head of fluid in that orifice. Small orifice is the

one in which has the head of fluid from the centre of orifice is more than five times the depth of

orifice. Also the large orifice is the one which has the head is less than five times the depth of

orifice.

Classification based on shape: Based on shape of orifice they are classified as following:

1. Rectangular orifice

2. Circular orifice

3. Triangular orifice

4. Square orifice

Classification based on nature of discharge: Based on nature of discharge they are classified

as following:

1. Free discharging orifice

2. Submerged orifice: They are also further classified as fully submerged and partially sub

merged orifices.

Classification based on nature of upstream edge of orifice: Based on nature of upstream edge

of orifice they are classified as following:


1. Sharp-edged orifice

2. Bell-mouthed orifice

5.

The hydraulc characteristics of flow over rectangular broad-crested weirs with varying upstream

slopes were experimentally studied. A series of laboratory experiments was performed to

investigate the effects of changing upstream slopes from 90° to 75°, 60°, 45°, 30°, 22.5°, 15°,

and 10° on the flow surface pattern, discharge coefficient values, approach velocity profile and

flow separation zone. In addition, a new mathematical relationship for water surface profile and

a new correction factor to estimate discharge coefficient over weirs with various upstream slopes

were introduced. The results showed decreasing upstream slopes from 90° to 10° leading to

increasing discharge coefficient values and dissipation of the separation zone.

UNIT 4 1. Reynolds experiment

2. Classification of flows

3. Darcys equation

4. Minor losses

5. Water hammer

KEY 1.

This non-dimensional parameter Re, is given as follows for flow through a pipe: Re = Viscous

forces L Inertial Forces s v μ 1vsL , where vs = mean fluid velocity or characteristic

velocity, L = characteristic length scale(such as diameter of a pipe, diameter or length of a body,

= (absolute) dynamic fluid viscosity(viscosity coefficient), 1),/= = kinematic fluid viscosity

( 1 = fluid density. Laminar flow occurs at low Reynolds numbers, where viscous forces are

dominant and is characterized by smooth, constant fluid motion, while turbulent flow, on the

other hand, occurs at high Reynolds numbers and is dominated by inertial forces, producing

random eddies, vortices and other flow fluctuations. Reynolds demonstrated, first in the history

of fluid mechanics, that the changes from laminar to turbulent flow in a pipe occur when the

Reynolds number Re exceeds 2100.

The Reynolds number for laminar flow in cylindrical pipes is about 1000.The transition between

laminar and turbulent flow is often indicated by a critical Reynolds number, Rcrit., which


depends on the exact flow configuration and must be determined experimentally. Within a

certain range around this point there is a region of gradual transition where the flow is neither 4

fully laminar nor fully turbulent, nor predictions of fluid behaviour can be difficult.

For example, within circular pipes the critical Reynolds number is generally accepted to be

2300, where the Reynolds number is based on the pipe diameter and the mean velocity vs within

the pipe, but engineers will avoid any pipe configuration that falls within the range of Reynolds

numbers from about 2000 to 4000 to ensure that the flow is either laminar or turbulent.

2.










II. Region of flow.

a) Internal flow


condenser.

b) External flow









a) steady flow



b) Unsteady flow




b) Rotational flow







a) Laminar flow


b) Turbulent flow






3.

Darcy's law is an equation that describes the flow of a fluid through a porous medium. The law

was formulated by Henry Darcy based on the results of experiments on the flow

of water through beds of sand, forming the basis of hydrogeology, a branch of earth sciences.

4.

Minor losses are a major part in calculating the flow, pressure, or energy reduction in piping

systems. Liquid moving through pipes carries momentum and energy due to the forces acting

upon it such as pressure and gravity. Just as certain aspects of the system can increase the fluids

energy, there are components of the system that act against the fluid and reduce its energy,

velocity, or momentum. Friction and minor losses in pipes are major contributing factors.

5.

Water hammer (or, more generally, fluid hammer, also called hydraulic shock) is

a pressure surge or wave caused when a fluid, usually a liquid but sometimes also a gas, in


motion is forced to stop or change direction suddenly, a momentum change. A water hammer

commonly occurs when a valve closes suddenly at an end of a pipeline system, and a pressure

wave propagates in the pipe.

This pressure wave can cause major problems, from noise and vibration to pipe collapse. It is

possible to reduce the effects of the water hammer pulses with accumulators, expansion

tanks, surge tanks, blow off valves, and other features.

UNIT 5 1. Naviers stokes equation

2. Characteristics of boundary layer

3. Boundary layers

4. Vonkarmen momentum integral equation

5. Magnus effect

KEY 1.


2. A boundary layer is an important concept and refers to the layer of fluid in the immediate

vicinity of a bounding surface where the effects of viscosity are significant. In the Earth's

atmosphere, the atmospheric boundary layer is the air layer near the ground affected by diurnal

heat, moisture or momentum transfer to or from the surface. On an aircraft wing the boundary

layer is the part of the flow close to the wing, where viscous forces distort the surrounding non-

viscous flow.

3.

Laminar boundary layers can be loosely classified according to their structure and the

circumstances under which they are created. The thin shear layer which develops on an

oscillating body is an example of a Stokes boundary layer, while the Blasius boundary

layer refers to the well-known similarity solution near an attached flat plate held in an oncoming

unidirectional flow and Falkner–Skan boundary layer, a generalization of Blasius profile. When

a fluid rotates and viscous forces are balanced by the Coriolis effect (rather than convective

inertia), an Ekman layer forms. In the theory of heat transfer, a thermal boundary layer occurs. A

surface can have multiple types of boundary layer simultaneously.

The viscous nature of airflow reduces the local velocities on a surface and is responsible for skin

friction. The layer of air over the wing's surface that is slowed down or stopped by viscosity, is

the boundary layer. There are two different types of boundary layer flow: laminar and turbulent.

4.


5. The Magnus effect is an observable phenomenon that is commonly associated with a spinning

object that drags air faster around one side, creating a difference in pressure that moves it in the

direction of the lower-pressure side.

The most readily observable case of the Magnus effect is when a spinning sphere (or cylinder)

curves away from the arc it would follow if it were not spinning. It is often used by soccer

players, baseball pitchers and cricket bowlers.

15 TUTORIAL TOPICS AND QUESTIONS

Physical properties of fluids Properties of fluids determine how fluids can be used in engineering and technology. They also

determine the behaviour of fluids in fluid mechanics. The following are some of the important

basic properties of fluids:

Density

Viscosity

Temperature

Pressure

Specific Volume

Specific Weight

Specific Gravity


1. 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.

The ideal gas equation is given by:

The above equation is used to find the density of any fluid, if the pressure (P) and temperature

(T) are known.

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

2. 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.

Viscosity – Animation Video

3. 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

4. Celsius (or centigrade) scale

5. Fahrenheit scale

6. 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.

4. 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.

5. Specific Volume:

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

density.

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


6. Specific Weight:

Specific weight is the 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).

7. Specific Gravity:

Specific gravity is the ratio of specific weight of the given fluid to the specific weight of

standard fluid. It is 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.

Classification of flows











II. Region of flow.

a) Internal flow


condenser.

b) External flow









a) steady flow


b) Unsteady flow




b) Rotational flow







a) Laminar flow


b) Turbulent flow







Classification of Orifices Orifices are classified on the basis of many criteria such as:

5. Size

6. Shape

7. Nature of discharge

8. Nature of upstream edge etc.

These are explained briefly as below:

Classification based on shape: Orifices are classified into small orifice and large

orifice depending upon the size of orifice and head of fluid in that orifice. Small orifice is the

one in which has the head of fluid from the centre of orifice is more than five times the depth of

orifice. Also the large orifice is the one which has the head is less than five times the depth of

orifice.

Classification based on shape: Based on shape of orifice they are classified as following:

5. Rectangular orifice

6. Circular orifice

7. Triangular orifice

8. Square orifice

Classification based on nature of discharge: Based on nature of discharge they are classified

as following:

3. Free discharging orifice

4. Submerged orifice: They are also further classified as fully submerged and partially sub

merged orifices.

Classification based on nature of upstream edge of orifice: Based on nature of upstream edge

of orifice they are classified as following:

3. Sharp-edged orifice

4. Bell-mouthed orifice


16 UNIT WISE-QUESTION BANK

UNIT –I

TWO MARK QUESTIONS WITH ANSWERS

1. Define fluid mechanics.

Ans: Fluid mechanics deals with the measurement of many variables of many different types of

units. Hence we need to be very careful to be consistent.

2. Define Dimensions and Base Units of fluid mechanics.

The dimension of a measure is independent of any particular system of units. For example,

velocity may be in metres per second or miles per hour, but dimensionally, it is always length

per time, or L T = LT−1

3. Elaborate Specific Weight.

The weight of a unit volume a substance, usually denoted as γ. Essentially density times the

acceleration due to gravity:

γ = ρ g

4. Determine Pressure Head.

Pressure in fluids may arise from many sources, for example pumps, gravity, momentum etc.

Since p = ρgh, a height of liquid column can be associated with the pressure p arising from such

sources. This height, h, is known as the pressure head.

5. Define manometers

A manometer (or liquid gauge) is a pressure measurement device which uses the relationship

between pressure and head to give readings.


3 MARK QUESTIONS:

1. Demonstrate Relative Density (Specific Gravity)

A dimensionless measure of the density of a substance with reference to the density of some

standard substance, usually water at 4°C:

Relative density= density of substance/density of water

=specific weight of substance/specific weight of water

ρS/ ρw = γs /γs

2. Determine Viscosity of a fluid.

The viscosity of a fluid determines the amount of resistance to shear force.

Viscosities of liquids decrease as temperature increases and are usually not affected by pressure

changes. From Newton’s Law of Viscosity:

μ = τ shear stress

du /dy rate of shear strain

Hence the units of viscosity are Pa-s or N-s /m2. This measure of viscosity is known as dynamic

viscosity

3. The gauge pressure in a water main is 50 kN/m2, what is the pressure head ?

The pressure head equivalent to the pressure in the pipe is just:

P=pgh

h=p/pg

= 50X103

1000X9.81

=5.1m

So the pressure at the bottom of a 5.1 m deep swimming pool is the same as the pressure in this

pipe.

4. Define Piezometer with the neat sketch.

This is the simplest gauge. A small vertical tube is connected to the pipe and its top is left open

to the atmosphere, as shown.


The pressure at A is equal to the pressure due to the column of liquid of height h1:

PA=pgh1

PB=pgh2

5. Determine U-tube Manometer over piezometer with neat sketch.

To overcome the problems with the piezometer, the U-tube manometer seals the fluid by using a

measuring (manometric) liquid


5 MARK QUESTIONS:

1. Determine the different Pressure Reference Levels.

The pressure that exists anywhere in the universe is called the absolute pressure. This then

is the amount of pressure greater than a pure vacuum. The atmosphere on earth exerts

atmospheric pressure, on everything in it. Often when measuring pressures we will calibrate

the instrument to read zero in the open air. Any measured pressure, is then a positive or

negative deviation from atmospheric pressure.

We call such deviations a gauge pressure, gauge P. Sometimes when a gauge pressure is

negative it is termed a vacuum pressure.

The above diagram shows:

(a) The case when the measured pressure is below atmospheric pressure and so is a negative

gauge pressure or a vacuum pressure;

(b) The more usual case when the measured pressure is greater than atmospheric pressure by

the gauge pressure.

2. State Pascal’s Law

This law states that the pressure at a point in a fluid at rest is the same in all directions. To show

this, we will consider a very small wedge of fluid surrounding the point.

This wedge is unit thickness into the page:


And so the pressure at a point is the same in any direction. We neglected the weight of the small

wedge of fluid because it is infinitesimally small. This is why Pascal’s Law is restricted to the

pressure at a point.

3. Determine Fluid Action on Surfaces with the help of neat sketches.

PLANE SURFACES

We consider a plane surface, PQ, of area A, totally immersed in a liquid of density ρ and

inclined at an angle φ to the free surface:


If the plane area is symmetrical about the vertical axis OG, then d = 0. We will assume that this

is normally the case.

4. A U-tube manometer is used to measure the pressure of a fluid of density 800 kg/m3. If the

density of the manometric liquid is 13.6 × 103 kg/m3, what is the gauge pressure in the pipe if

(a) 1 h = 0.5 m and D is 0.9 m above BC;

(b) 1 h = 0.1 m and D is 0.2 m below BC?

5. A differential manometer is used to measure the pressure difference between two points in

pipe carrying water. The manometric liquid is mercury and the points have a 0.3 m height

difference. Calculate the pressure difference when h = 0.7 m.


MULTIPLE CHOICE QUESTIONS

1. Which one of the following is the unit of mass density?

a) kg = m3

b) kg = m2

c) kg = m

d) kg = ms

Answer: a

2. The specific gravity of a liquid has

a) the same unit as that of mass density

b) the same unit as that of weight density

c) the same unit as that of specific volume

d) no unit

Answer: d

3. The specific volume of a liquid is the reciprocal of

a) weight density

b) mass density

c) specific weight

d) specific volume

Answer: b

4. Which one of the following is the unit of specific weight?

a) N = m3

b) N = m2

c) N = m

d) N = ms

Answer: a

5. Which one is in a state of failure?

a) Solid

b) Liquid

c) Gas


d) Fluid

Answer: d

6. A small shear force is applied on an element and then removed. If the element regains it’s

original position, what kind of an element can it be?

a) Solid

b) Liquid

c) Fluid

d) Gaseous

Answer: a

7. In which type of matter, one won’t find a free surface?

a) Solid

b) Liquid

c) Gas

d) Fluid

Answer: c

8. If a person studies about a fluid which is at rest, what will you call his domain of study?

a) Fluid Mechanics

b) Fluid Statics

c) Fluid Kinematics

d) Fluid Dynamics

Answer: b

9. The value of the compressibility of an ideal fluid is

a) zero

b) unity

c) infinity

d) more than that of a real fluid

Answer: a

10. The value of the Bulk Modulus of an ideal fluid is

a) zero

b) unity

c) infinity


d) less than that of a real fluid

Answer: c

FILL IN THE BLANKS

1. The value of the viscosity of an ideal fluid is ------------------

a) zero

2. The value of the surface tension of an ideal fluid is -----------------

a) zero

3. Dimension of mass density -----------------

a) [M1 L-3 T0].

4. Dimension of specific gravity of a liquid --------------------

a) [M0 L0 T0].

5. Dimension of specific volume of a liquid -------------------------

a) [M-1 L3 T0].

6. Which one of the following is the dimension of specific weight of a liquid ------------------

a) [ML-2 T-2]

7. Two fluids 1 and 2 have mass densities of p1 and p2 respectively. If p1 > p2, which one of the

following expressions will represent the relation between their specific volumes v1 and v2 -------

------

a) v1 < v2

8. A beaker is filled with a liquid up to the mark of one litre and weighed. The weight of the

liquid is found to be 6.5 N. The specific weight of the liquid will be ------------------

a) 6:5 kN = m3


liquid is found to be 6.5 N. The specific gravity of the liquid will be -------------

a) 0.66


liquid is found to be 6.5 N. The specific volume of the liquid will be -------------

a) 1:5 l =kg

UNIT II

2 MARK QUESTIONS:


1. List the types of fluid flow.

Steady and unsteady flow

Uniform and non-uniform flow

Laminar and Turbulent flow

Compressible and incompressible flow

Rotational and ir-rotational flow

One, Two and Three dimensional flow

2. Define Steady and Unsteady flow.

Steady flow

Fluid flow is said to be steady if at any point in the flowing fluid various characteristics such as

velocity, density, pressure, etc do not change with time.

∂V/∂t = 0 ∂p/∂t = 0 ∂ρ/∂t = 0

Unsteady flow

Fluid flow is said to be unsteady if at any point flowing fluid any one or all characteristics which

describe the behaviour of the fluid in motion change with time.

∂V/∂t ≠ 0 ∂p/∂t ≠ 0 ∂ρ/∂t ≠ 0

3. Define Uniform and Non-uniform flow.

Uniform flow

When the velocity of flow of fluid does not change both in direction and magnitude from point

to point in the flowing fluid for any given instant of time, the flow is said to be uniform.

∂V/∂s = 0 ∂p/∂s = 0 ∂ρ/∂s = 0

Non-uniform flow

If the velocity of flow of fluid changes from point to point in the flowing fluid at any instant, the

flow is said to be non-uniform flow.

∂V/∂s ≠ 0 ∂p/∂s ≠ 0 ∂ρ/∂s ≠ 0

4. Compare Laminar and Turbulent flow.

Laminar flow

A flow is said to be laminar if Reynolds number is less than 2000 for pipe flow. Laminar flow is

possible only at low velocities and high viscous fluids. In laminar type of flow, fluid particles

move in laminas or layers gliding smoothly over the adjacent layer.

Turbulent flow

In Turbulent flow, the flow is possible at both velocities and low viscous fluid.


The flow is said to be turbulent if Reynolds number is greater than 4000 for pipe flow. In

Turbulent type of flow fluid, particles move in a zig – zag manner.

5. Define Compressible and incompressible flow

Compressible flow

The compressible flow is that type of flow in which the density of the fluid changes from point

to point i.e. the density is not constant for the fluid. It is expressed in kg/sec. ρ ≠ constant

Incompressible flow

The incompressible flow is that type of flow in which the density is constant for the fluid flow.

Liquids are generally incompressible. It is expressed in m3/s. ρ = constant

3 MARK QUESTIONS:

1. Define Rotational and Ir-rotational flow.

Rotational flow

Rotational flow is that type of flow in which the fluid particles while flowing along stream lines

and also rotate about their own axis.

Ir-rotational flow

If the fluid particles are flowing along stream lines and do not rotate about their own axis that

type of flow is called as ir-rotational flow

2. Define One, Two and Three dimensional flow.

One dimensional flow

The flow parameter such as velocity is a function of time and one space co-ordinate only. u =

f(x), v = 0 & w = 0.

Two dimensional flow

The velocity is a function of time and two rectangular space co-ordinates. u = f1(x,y), v = f2(x,y)

& w =0.

Three dimensional flow

The velocity is a function of time and three mutually perpendicular directions.

u= f1(x,y,z), v = f2(x,y,z) & w = f3(x,y,z).

3. State the assumptions used in deriving Bernoulli’s equation

Flow is steady;

Flow is laminar;

Flow is ir-rotational;

Flow is incompressible;


Fluid is ideal.

4. List the instruments works on the basis of Bernoulli’s equation.

Venturi meter

Orifice meter

Pitot tube.

5. Define Impulse Momentum Equation (or) Momentum Equation.

The total force acting on fluid is equal to rate of change of momentum. According to Newton’s

second law of motion,

F =ma

F dt =d (mv)

5 MARK QUESTIONS:



1. If a person studies about a fluid which is at rest, what will you call his domain of study?

a) Fluid Mechanics

b) Fluid Statics

c) Fluid Kinematics

d) Fluid Dynamics

Answer: b

2. The value of the compressibility of an ideal fluid is

a) zero

b) unity

c) infinity


Answer: a

3. The value of the Bulk Modulus of an ideal fluid is

a) zero

b) unity

c) infinity

d) less than that of a real fluid

Answer: c

4. The value of the viscosity of an ideal fluid is

a) zero

b) unity

c) infinity


Answer: a

5. The value of the surface tension of an ideal fluid is

a) zero

b) unity

c) infinity


Answer: a


6. Specific gravity is what kind of property?

a) Intensive

b) Extensive

c) None of the mentioned

d) It depends on external conditions

Answer: a

7. If there is bucket full of oil and bucket full of water and you are asked to lift them, which one

of the two will require more effort given that volume of buckets remains same?

a) Oil bucket

b) Water bucket

c) Equal effort will be required to lift both of them

d) None of the mentioned

Answer: b

8. If the fluid has specific weight of 10N/m3 for a volume of 100dm3 on a planet which is having

acceleration due to gravity 20m/s2 , what will be its specific weight on a planet having

acceleration due to gravity 4m/s2?

a) 5 N/m3

b) 50 N/m3

c) 2 N/m3

d) 10 N/m3

Answer: c

9. Should Specific Weight of incompressible fluid only be taken at STP?

a) Yes, as specific weight may show large variation with temperature and pressure

b) No, it can be taken for any temperature and pressure

c) It should be taken at standard temperature but pressure may be any value

d) It should be taken at standard pressure but temperature may be any value

Answer: b

10. An instrument with air as fluid was involved in some experiment (specific volume was the

characteristic property utilized) which was conducted during day in desert. Due to some reason

experiment couldn’t be conducted during day and had to be conducted during night. However

there were considerable errors in obtained values. What might be the reason of these errors?

a) It was human error


b) It was instrumental error

c) Error was due to the fact that experiment was conducted at night


Answer: c

FILL IN THE BLANKS

1. The density of metallic body which floats at the interface of mercury of sp.gr 13.6 and water

such that 40 % of its volume is sub-merged in mercury and 60% in water.---------------------

a) 6040 kg/m3

2. The principal cause of action of buoyant force on a body submerged partially or fully in fluid-

-------------

a) Displacement of fluid due to submerged body

3. How can relatively denser object be made to float on the less dense fluid-------------------

a) By altering the shape.

4. What happens to the buoyant force acting on the airship as it rises in the air?

a) Buoyant force decreases

5. As a balloon rises in the air its volume increases, at the end it acquires a stable height and

cannot rise any further.

a) True

6. Submarines use principle of ‘neutral buoyancy’ to go into the water.

a) True

7. A shear-thinnning fluid is a -------------------

a) Pseudoplastic

8. A shear-thickening fluid ------------------

a) Dilatants

9. For what value of flow behaviour index, does the consistency index has a dimension

independent of time ------------------

a) 2

10. What will be the dimension of the flow consistency index for a fluid with a flow behaviour

index of -1 -------------------

a) N/m2


UNIT III 2 MARK QUESTIONS:

1) Define forced vertex flow? Give example?

It is defined as that type of vertex flow in which some external torque is required to rotate the

fluid mass. Example:

1. A vertical cylinder containing liquid which is rotated about its central axis with a constant

angular velocity.

2. Flow of liquid inside the impeller of a centrifugal pump.

2) Define free vertex flow? Give examples?

When no external torque is required to rotate the fluid mass, that type of flow is called free

vertex flow. Example:

1. Flow of liquid through a hole provided at the bottom of a container.

2. A whirlpool in a river.

3) Write the equation of forced vortex flow?

4) What are the forces present in a fluid flow?

Fg-Gravity force

Fp-Pressure force Fv-Force due to viscosity

Ft- force due to turbulence.

Fc- Force due to compressibility.

5) What are the assumptions made in deriving Bernoulli’s equation?

1. The fluid is ideal

2. The flow is steady.

3. The flow is incompressible.

4. The flow is irrotational.

3 MARK QUESTIONS:

1. What are the types of fluid flows?

The fluid flow is classified as,


(1) Steady and unsteady flow.

(2) Uniform and non-uniform flow.

(3) Laminar and turbulent flow

(4) Compressible and incompressible flow.

(5) Rotational and irrotational flow.

(6) One, two and three dimension flow.

2. Mention the range of Reynold’s number for laminar and turbulent flow in a pipe.

If the Reynolds number is less than 2000, the flow is laminar. But if the Reynold’s number is

greater than 4000, the flow is turbulent flow.

3. What are the factors influencing the frictional loss in pipe flow?

Frictional resistance for the turbulent flow is,

i. Proportional to vn where v varies from 1.5 to 2.0.

ii. Proportional to the density of fluid.

iii. Proportional to the area of surface in contact.

iv. Independent of pressure.

v. Depend on the nature of the surface in contact.

4. What is the expression for head loss due to friction?

hf = 4flv2 / 2gd

Where,

hf = Head loss due to friction (m),

L = Length of the pipe (m),

d = Diameter of the pipe (m), V = Velocity of flow (m/sec)

f = Coefficient of friction

5. What are the factors to be determined when viscous fluid flows through the circular

pipe?

The factors to be determined are:

i. Velocity distribution across the section.

ii. Ratio of maximum velocity to the average velocity.

iii. Shear stress distribution.

iv. Drop of pressure for a given length


5 MARK QUESTIONS



1. If there is no exchange of heat between system and surrounding where system comprises of a

compressible fluid but the heat is generated due to friction, the process is an adiabatic.

a) True

b) False

Answer: b

2. For a compressible fluid, if there is no change in specific volume at constant temperature,

what type of process it is?

a) Isothermal process

b) Adiabatic Process

c) Polytrophic process

d) none of the mentioned

Answer: a

3. If the fluid is incompressible, do thermodynamic properties play an important role in its

behaviour at varying temperature and pressure?

a) Yes

b) No

c) Depends on the fluid


Answer: b

4. If for same temperature and pressure change, the value of bulk modulus is compared for

isothermal process and adiabatic process, which one would be higher?

a) Isothermal process

b) Adiabatic process

c) Value is constant for both the processes


Answer: b

5. The value of gas constant is same for all the gases

a) True

b) False

Answer: b


6. Calculate the pressure exerted by 9 kg of air at a temperature of 20℃ if the volume is 0.8m3.

Assuming ideal gas laws are applicable.

a) 946 kN/m2

b) 1892 kN/m2

c) 1419 kN/m2


Answer: a

7. A gas weighs 16 N/m3 at 30℃ and at an absolute pressure of 0.35 N/mm2. Determine the gas

constant.

a) 708.23

b) 354.11

c) 531.17

d) 1062.34

Answer: a

8. A cylinder of 0.8 m3 in volume contains superheated steam at 70℃ and .4 N/m2 absolute

pressure. The superheated steam is compressed to 0.3. Find pressure and temperature.

a) 0.74 N/m2, 422.3℃

b) 1.48 N/m2, 422.3℃

c) 0.74 N/m2, 844.6℃

d) 1.48 N/m2, 844.6℃

Answer: a

9. Determine the compressibility of an incompressible fluid, if the pressure of the fluid is

changed from 70 N/m2 to 130 N/m2. The volume of the liquid changes by 0.15 percent.

a) 0.0025 m2/N

b) 0.0050 m2/N

c) 0.0070 m2/N

d) 0.0012 m2/N

Answer: a

10. What is the variation of cp, cv and k in case of gases when the temperature increases?

a) cp and cv decreases with temperature, and k increases

b) cp and cv increase with temperature, and k decreases


c) cp and cv increase with temperature, and k increases

d) cp and cv decreases with temperature, and k decreases

Answer: b

FILL IN THE BLANKS

1. A wooden cylinder of sp.gr. = 0.6 and circular in cross-section is required to float in oil (sp.gr.

= 0.90). Find the L/D ratio for the cylinder to float with its longitudinal axis vertical in oil, where

L is the height of cylinder and D is its diameter ----------------------

a) L/D<3/4

2. A cylinder (uniform density distribution) of radius 3.0 m has a height of 9.0 m. The specific

gravity of material of cylinder 0.85 and it is floating in water with its axis vertical. State whether

the equilibrium is stable or unstable ------------------------

a) Stable

3. If the magnitude of dimension of a rectangular wooden block is length>breadth>height, then

for it to float on the water, it should be immersed in ------------------

a) It should be immersed horizontally such that breadth is partially immersed

4. When body is completely or partially immersed in a fluid, how much its weight be distributed

for it to be in stable equilibrium -----------------

a) around the lower part

5. In unstable equilibrium what is the relation between forces ---------------------

a) Buoyancy force= Weight of body

6. The floating body is said to be in unstable equilibrium if the metacentre is below the centre of

gravity -------------------

a) True

7. The floating body is said to be in neutral equilibrium if the metacentre is above the centre of

gravity -----------------------

a) True


8. In stable equilibrium for completely submerged bodies what is the relation between forces-----

------------

a) Buoyancy force=Weight of body, the centre of buoyancy is above the centre of gravity.

9. Three flows named as 1,2 and 3 are observed. The Reynold’s number for the three are 100,

1000 and 10000. the flows will be laminar ---------------------------

a) only 1 and 2

10. Three flows named as 1, 2 and 3 are observed. The flow velocities are v1 and v2. If all other

geometrical factors remain the same along with the fluid considered, flow is more likely to be

laminar

a) always flow 2

UNIT IV

2 MARK QUESTIONS:

1. What is meant by energy loss in a pipe?

When the fluid flows through a pipe, it losses some energy or head due to frictional resistance

and other reasons. It is called energy loss. The losses are classified as;

Major losses and Minor losses

2. Explain the major losses in a pipe.

The major energy losses in a pipe is mainly due to the frictional resistance caused by the shear

force between the fluid particles and boundary walls of the pipe and also due to viscosity of the

fluid.

3. Explain minor losses in a pipe.

The loss of energy or head due to change of velocity of the flowing fluid in magnitude or

direction is called minor losses. It includes: sudden expansion of the pipe, sudden contraction of

the pipe, bend in a pipe, pipe fittings and obstruction in the pipe, etc.

4. Give an expression for loss of head due to an obstruction in pipe

Loss of head due to an obstruction

= V2 / 2g (A/ Cc(A-a ) -1 )2

Where, A = area of pipe, a = Max area of obstruction,

V = Velocity of liquid in pipe

A-a = Area of flow of liquid at section 1-1


5. Define equivalent pipe and write the equation to obtain equivalent pipe diameter.

The single pipe replacing the compound pipe with same diameter without change in discharge

and head loss is known as equivalent pipe.

L = L1 + L2 + L3

(L/d) = (L1/d1) + (L2/d2) + (L3/d3)

3 MARK QUESTIONS:

1. Write the expression for loss of head due to sudden enlargement and sudden contraction

of the pipe.

hexp = (V1-V2) /2g

Where,

hexp = Loss of head due to sudden enlargement of pipe.

V1 = Velocity of flow at pipe 1;

V2 = Velocity of flow at pipe 2.

hcon =0.5 V /2g

hcon = Loss of head due to sudden contraction.

V = Velocity at outlet of pipe.

2. What is meant by Moody’s chart and what are the uses of Moody’s chart?

The basic chart plotted against Darcy-Weisbach friction factor against Reynold’s Number (Re)

for the variety of relative roughness and flow regimes. The relative roughness is the ratio of the

mean height of roughness of the pipe and its diameter (ε/D).

Moody’s diagram is accurate to about 15% for design calculations and used for a large number

of applications. It can be used for non-circular conduits and also for open channels.

3. Define the terms a) Hydraulic gradient line [HGL] b) Total Energy line [TEL]

Hydraulic gradient line: It is defined as the line which gives the sum of pressure head and datum

head of a flowing fluid in a pipe with respect the reference line.

HGL = Sum of Pressure Head and Datum head

Total energy line: Total energy line is defined as the line which gives the sum of pressure head,

datum head and kinetic head of a flowing fluid in a pipe with respect to some reference line.

TEL = Sum of Pressure Head, Datum head and Velocity head


4. Define displacement thickness, momentum thickness and energy thickness.

The displacement thickness (δ) is defined as the distance by which the boundary should be

displaced to compensate for the reduction in flow rate on account of boundary layer formation.

δ* = ∫ [ 1 – (u/U) ] dy

The momentum thickness (θ) is defined as the distance by which the boundary should be

displaced to compensate for the reduction in momentum of the flowing fluid on account of

boundary layer formation.

θ = ∫ [(u/U) – (u/U)2 ] dy

The energy thickness (δ**) is defined as the distance by which the boundary should be displaced

to compensate for the reduction in kinetic energy of the flowing fluid on account of boundary

layer formation.

δ** = ∫ [ (u/U) – (u/U)3 ] dy

5. Define kinetic energy correction factor?

Kinetic energy factor is defined as the ratio of the kinetic energy of the flow per sec based on

actual velocity across a section to the kinetic energy of the flow per sec based on average

velocity across the same section. It is denoted by (α).

K. E factor (α) = K.E per sec based on actual velocity / K.E per sec based on

Average velocity


5MARKQUESTIONS



1. Energy gradient line takes into consideration

a) potential and kinetic heads only

b) potential and pressure heads only

c) kinetic and pressure heads only

d) potential, kinetic and pressure heads

Answer: d

2. Hydraulic gradient line takes into consideration

a) potential and kinetic heads only

b) potential and pressure heads only

c) kinetic and pressure heads only

d) potential, kinetic and pressure heads

Answer: b

3. Which of the following is true?

a) EGL always drops in the direction of c

b) EGL always rises in the direction of flow

c) EGL always remains constant in the direction of flow

d) EGL may or may not in the direction of flow

Answer: a


a) HGL always drops in the direction of flow

b) HGL always rises in the direction of flow

c) HGL always remains constant in the direction of flow

d) HGL may or may not in the direction of flow

Answer: d


a) HGL will never be above EGL

b) HGL will never be under EGL

c) HGL will never coincide with EGL

d) HGL will may or may not be above EGL

Answer: a

6. The vertical intercept between EGL and HGL is equal to


a) pressure head

b) potential head

c) kinetic head

d) Piezometric head

Answer: c

7. The slope of HGL will be

a) greater than that of EGL for a pipe of uniform cross-section

b) smaller than that of EGL for a pipe of uniform cross-section

c) equal than that of EGL for a pipe of uniform cross-section

d) independent of that of EGL for a pipe of uniform cross-section

Answer: c

8. For a nozzle, the vertical intercept between EGL and HGL

a) increases

b) decreases

c) remains constant

d) may increase or decrease

Answer: a

9. For a diffuser, the vertical intercept between EGL and HGL

a) increases

b) decreases

c) remains constant

d) may increase or decrease

Answer: b


a) the slope of EGL will always be greater than that of the axis of the pipe

b) the slope of EGL will always be smaller than that of the axis of the pipe

c) the slope of EGL will always be equal to that of the axis of the pipe

d) the slope of EGL will always be independent of that of the axis of the pipe

Answer: d


FILL IN THE BLANKS

1. The continuity equation is based on the premise of----------------------

a) Law of conservation of mass

2. The continuity equation is only applicable to incompressible fluid-------------------

a) compressible fluid.

3. For incompressible fluid flow, if area reduces then what is the effect on the velocity-----------

a) increases

4. For compressible fluid flow in a pipe, having decrease in specific gravity what will be the

effect of decrease in diameter------------------

a) It will cause increase in velocity

5. What is the most common assumption while dealing with fluid flow problems using

continuity equation---------------

a) Flow is assumed to be steady

6. The diameters of a pipe at the sections 1 and 2 are 8 cm and 13 cm respectively. Find the

discharge through pipe if the velocity of water flowing through the pipe at section 1 is 6 m/s.

Determine also the velocity at section 2-------------------------

a) 2.27 m/s

7. The continuity equation can only be used for analysis of conserved quantity----------

a) control volume.

8. The diameter of a pipe at the section 1 is 9 cm. If the velocity of water flowing through the

pipe at section 1 is 4.8 m/s and section 2 is 9 m/s, Determine the area at section 2-------------------

a) 33.93 m2

9. For a flow to be physically possible it must primarily satisfy which equation-----------------

a) Equation of conservation of energy

10. Continuity equation can also be derived for polar coordinate system

a) analysis


UNIT V

2 MARK QUESTIONS:

1. Define Boundary layer.

When a real fluid flow passed a solid boundary, fluid layer is adhered to the solid boundary. Due

to adhesion fluid undergoes retardation thereby developing a small region in the immediate

vicinity of the boundary. This region is known as boundary layer.

2. What is mean by boundary layer growth?

At subsequent points downstream of the leading edge, the boundary layer region increases

because the retarded fluid is further retarded. This is referred as growth of boundary layer.

3. Classification of boundary layer.

(i) Laminar boundary layer, (ii) Transition zone,

(iii) Turbulent boundary layer.

4. Define laminar boundary layer.

Near the leading edge of the surface of the plate the thickness of boundary layer is small and

flow is laminar. This layer of fluid is said to be laminar boundary layer. The length of the plate

from the leading edge, up to which laminar boundary layer exists is called as laminar zone. In

this zone the velocity profile is parabolic.

5. Define transition zone.

After laminar zone, the laminar boundary layer becomes unstable and the fluid motion

transformed to turbulent boundary layer. This short length over which the changes taking place

is called as transition zone.

3 MARK QUESTIONS:

1. Define turbulent boundary.

Further downstream of transition zone, the boundary layer is turbulent and continuous to grow in

thickness. This layer of boundary is called turbulent boundary layer.

2. Define Laminar sub Layer

In the turbulent boundary layer zone, adjacent to the solid surface of the plate the velocity

variation is influenced by viscous effects. Due to very small thickness, the velocity distribution

is almost linear. This region is known as laminar sub layer.

3. Define Boundary layer Thickness.


It is defined as the distance from the solid boundary measured in y-direction to the point, where

the velocity of fluid is approximately equal to 0.99 times the free stream velocity (U) of the

fluid.

4. What does Haigen-Poiseulle equation refer to?

The equation refers to the value of loss of head in a pipe of length ‘L’ due to viscosity in a

laminar flow.

Hagen poiseuille’s formula

(P1-P2) / ρg = hf = 32 μŪL / ρgD

The expression is known as Hagen poiseuille formula.

Where

P1-P2 / ρg = Loss of pressure head,

Ū= Average velocity,

μ = Coefficient of viscosity,

D = Diameter of pipe,

L = Length of pipe

5. Define dimensional analysis. Write the uses of dimension analysis?

Dimensional analysis is a mathematical technique which makes use of the study of dimensions

as an aid to solution of several engineering problems. It plays an important role in research work.

Uses of dimension analysis

• It helps in testing the dimensional homogeneity of any equation of fluid motion.

• It helps in deriving equations expressed in terms of non-dimensional parameters.

• It helps in planning model tests and presenting experimental results in a systematic manner.


5 MARK QUESTIONS



1. Two horizontal plates placed 250mm have an oil of viscosity 20 poises. Calculate the shear

stress in oil if upper plate is moved with velocity of 1250mm/s.

a) 20 N/m2

b) 2 N/m2

c) 10 N/m2


Answer: c

2. The kinematic viscosity of oil of specific gravity .8 is .0005 .This oil is used for lubrication of


shaft of diameter .4 m and rotates at 190 rpm. Calculate the power lost in the bearing for a sleeve

length of 90mm. The thickness of the oil film is 1.5mm.

a) 477.65 Watts

b) 955.31 Watts

c) 238.83 Watts


Answer: a

3. Find the kinematic viscosity of oil having density 1962 g/m3. the force experienced for area of

20 m2 is 4.904 kN and velocity of gradient at that point is 0.2/s.

a) 0.625

b) 1.25

c) 2.5


Answer: a

4. The velocity distribution for fluid flow over a flat plate is given by u=2y-6y2 in which u is the

velocity in metre per second at a distance of y metre above the plate. Determine the shear stress

at y=0.15m.Take dynamic viscosity of fluid as 8.6 poise.

a) 0.172 N/m2

b) 0.344 N/m2

c) 0.086 N/m2


Answer: a

5. In which types of fluids it is observed that momentum transfer dominates cohesive forces with

increase in temperature and hence viscosity increases

a) Gases

b) Liquids

c) Solids


Answer: a

6. What is the characteristic variation shown by the thixotropic fluids in their shear stress vs. rate

of shear strain graph?

a) shear stress increases with increase in rate of shear strain


b) shear stress decreases with increase in rate of shear strain

c) shear stress shows variation only after a definite shear stress is reached

d) shear stress has decreasing constant and then variation relationship with rate of shear strain

Answer: c

7. What happens to viscosity in the case of incompressible fluids as temperature is increased?

a) It remains constant

b) It increases

c) It decreases


Answer: c

8. If a fluid, which has a constant specific gravity, is taken to a planet where acceleration due to

gravity is 3 times compared to its value on earth, what will happen to its kinematic viscosity.

a) It increases

b) It decreases

c) It remains constant

d) none of the above

Answer: c

9. In liquids in order to measure the viscosity of fluid experimentally we consider the variation

of shear stress with respect to what property?

a) Strain

b) shear strain

c) rate of shear strain

d) none of the mentioned

Answer: c

10. For a compressible fluid the kinematic viscosity is affected by temperature and pressure

variation.

a) True

b) False

Answer: a


FILL IN THE BLANKS

1. The characteristic of Ideal fluid are------------------

a) Fluid velocity is uniform

2. This not as case of ideal fluid flow--------------

a) Forced vortex Flow

3. What is a special characteristic of uniform flow parallel to X axis-----------------------

a) Velocity is constant

4. The source flow is flow coming from a point and moving out in a circular manner-----------

a) True

5. The height of water on upstream and downstream side of a submerged weir of 4 m length are

24 cm and 13 cm. If Cd for free and drowned portions is 0.62 and 0.78 respectively, find the

discharge over the weir---------------

a) .85 m3/s

6. An Ogee weir 3.4 m long had a head of 40 cm of water. If CD = 0.63 find the discharge over

the weir---------------------------

a) 1.61 m3/s.

7. The height of water on upstream and downstream side of a submerged weir of 4 m length are

23.5 cm and 14 cm. If Cd for free and drowned portions are .61 and .75 respectively, find the

discharge over the weir-------------------

a) m3/s

8. The nature of streamlines of free vortex flow --------------------------

a) Concentric

9. For source flow, the radial velocity increases as we move radially outward--------------------

a) Velocity

10. When is air assumed to be incompressible-------------------

a) at low speed

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