Applications of fluid mechanics

Detailed report on applications of fluid mechanics

1. APPLICATIONS
OF FLUID
MECHANICS 

2. CONTENTS
PART-A
INTRODUCTION TO FLUID MECHANICS
1-DEFINATION OF FLUID AND BASICS
2-DIFFERENCE IN BEHAVIOUR OF FLUID AND
SOLID
3-BASIC LAWS GOVERNING FLUID MECHANICS
4-DIFFERENT APPROACHES IN STUDY OF FLUID
MECHANICS
A-Differential versus Integral Approach
B-Lagrangian versus Eulerian Approach
5-BRIEF HISTORY
6- SCOPE OF FLUID MECHANICS
PART-B
AREAS OF APPLICATION OF FLUID
MECHANICS
1-METEOROLOGY (WEATHER FORECASTING)
2-AEROSPACE AND AUTOMOBILE INDUSTRY
3-TURBOMACHINES AND HYDRAULICS

3. 4-FLUID AS COOLANT IN ENGINES, ELECTRONICS,
POWER PALNTS AND MANUFACTURING
NANOFLUIDS AS COOLANTS
(RECENT DEVELOPMENT)
5- PROCESS ENGINEERING, REFRIGERATION AND
HVAC SYSTEMS
6-RENEWABLE ENERGY SYSTEMS BASED ON
FLUID MECHANICS
A-WIND POWER
B- WAVE POWER
7-BIOMEDICAL APPLICATIONS
ARTIFICIAL HEARTS
8-SMART FLUIDS
A-MAGNETORHEOLOGICAL AND
ELECTRORHEOLOGICAL FLUIDS
B-FERROFLUID
MEDICAL APPLICATIONS
9- APPLICATIONS IN SPORTS
SHARK SKIN IN SWIM SUITS
10-FORECASTING NATURAL DISASTERS
TROPICAL CYCLONE
11-MEMS

4. PART-A
INTRODUCTION TO FLUID
MECHANICS
1-DEFINATION OF FLUID AND BASICS
Fluid mechanics is the branch of physics that studies the mechanics of
fluids (liquids, gases, and plasmas) and the forces on them. It is the study
of fluids at rest or in motion. It is a branch of continuum mechanics, a
subject which models matter without using the information that it is made
out of atoms; that is, it models matter from a macroscopic viewpoint
rather than from microscopic.
A fluid is a substance that deforms continuously under the application of a
shear (tangential) stress no matter how small the shear stress may be.
Fluids tend to flow when we interact with them while solids tend to deform
or bend. We can also define a fluid as any substance that cannot sustain a
shear stress when at rest.

5. 2-DIFFERENCE IN BEHAVIOUR OF FLUID AND
SOLID
A fluid in contact with a solid surface does not slip—it has the same
velocity as that surface because of the no-slip condition, an experimental
fact. The amount of deformation of the solid depends on the solid’s
modulus of rigidity. The rate of deformation of the fluid depends on the
fluid’s viscosity μ. We refer to solids as being elastic and fluids as being
viscous. Substances which exhibits both springiness and friction; they are
viscoelastic. Many biological tissues are viscoelastic.
3-BASIC LAWS GOVERNING FLUID MECHANICS
Analysis of any problem in fluid mechanics includes statement of the basic
laws governing the fluid motion. The basic laws, which are applicable to
any fluid, are-
1. The conservation of mass
2. Newton’s second law of motion
3. The principle of angular momentum
4. The first law of thermodynamics
5. The second law of thermodynamics
4-DIFFERENT APPROACHES IN STUDY OF FLUID
MECHANICS
A-Differential versus Integral Approach
The basic laws that we apply in our study of fluid mechanics can be
formulated in terms of infinitesimal or finite systems and control volumes.
In the first case the resulting equations are differential equations; solution
of the differential equations of motion provides a means of determining
the detailed behavior of the flow. We often are interested in the gross
behavior of a device; in such cases it is more appropriate to use integral
formulations of the basic laws.
B-Lagrangian versus Eulerian Approach
Method of description that follows the particle is referred to as the
Lagrangian method of description. In Lagrangian approach we analyze a
fluid flow by assuming the fluid to be composed of a very large number of
particles whose motion must be described.
In control volume analyses, it is convenient to use the field, or Eulerian,
method of description, which focuses attention on the properties of a flow
at a given point in space as a function of time. In the Eulerian method of
description, the properties of a flow field are described as functions of
space coordinates and time.

6. 5-BRIEF HISTORY
SCIENTISTS/ENGINEERSCONTRIBUTION
ARCHIMEDES FLUID STATICS
LEONARDO DA VINCI FLUID STATICS(OBSERVATIONS AND
EXPERIMENTS)
TORICELLI INVENTED THE BAROMETER
ISSAC NEWTON INVESTIGATED VISCOSITY
BLAISE PASCAL HYDROSTATICS
BERNOULLI HYDRODYNAMICS
LEONARD EULER, R D ALEMBERT, J L
LAGRANGE, PIERRE SIMON
LAPLACE, S D POISSON
INVISCID FLOW
J L M POISEUILLI, GOTTHILF
HAGEN,CLAUDE-LOUIS NAVIER,
GEORGE GABRIEL STOKES, LUDWIG
PRANDTL, THEODORE VON KARMAN
VISCOUS FLOW
OSBORNE REYNOLDS, ANDREY
KOLMOGROV,GEOFFREY INGRAM
TAYLOR
FLUID VISCOSITY AND TURBULENCE
6-SCOPE OF FLUID MECHANICS
It has traditionally been applied in areas as the design of canal and dam
systems; the design of pumps, compressors, and piping and ducting used
in the water and air conditioning systems of homes and businesses, piping
systems needed in chemical plants; the aerodynamics of automobiles and
sub- and supersonic airplanes; and the development of many different
flow measurement devices such as gas pump meters.
Many exciting areas have developed in the last quarter-century. Some
examples include environmental and energy issues (e.g., containing oil
slicks, large-scale wind turbines, energy generation from ocean waves,
the aerodynamics of large buildings, and the fluid mechanics of the
atmosphere and ocean and of phenomena such as tornadoes, hurricanes,
and tsunamis, biomechanics (e.g., artificial hearts and valves and other
organs, sports, “smart fluids” (e.g., in automobile suspension systems to
optimize motion under all terrain conditions, military uniforms containing
a fluid layer that is “thin” until combat, when it can be “stiffened” to give
the soldier strength and protection, and fluid lenses with humanlike
properties for use in cameras and cell phones); and microfluids (e.g., for
extremely precise administration of medications). We will discuss these
areas in details.

7. PART-B
AREAS OF APPLICATION OF FLUID
MECHANICS
1-METEOROLOGY (WEATHER
FORECASTING)
Weather forecasting is the application of science and technology to
predict the state of the atmosphere for a given location. Weather
forecasts are made by collecting quantitative data about the current state
of the atmosphere at a given place and using scientific understanding of
atmospheric processes to project how the atmosphere will change.
Once an all-human endeavor based mainly upon changes in barometric
pressure, current weather conditions, and sky condition, weather
forecasting now relies on computer-based models that take many
atmospheric factors into account.
There are a variety of end uses to weather forecasts. Weather warnings
are important forecasts because they are used to protect life and property.
Forecasts based on temperature and precipitations are important to
agriculture, and therefore to traders within commodity forecasts can be
used to plan activities around these events, and to plan ahead and
survive them.

8. It was not until the 20th century that advances in the understanding of
atmospheric physics led to the foundation of modern numerical weather
prediction. In 1922, English
scientist Lewis Fry Richardson published “Weather Prediction By Numerical
Process”,
The first computerized weather forecast was performed by a team led by
the mathematician
John von Neumann; von Neumann publishing the paper Numerical
Integration of the Barotropic Vorticity Equation in 1950. Practical use of
numerical weather prediction began in 1955, spurred by the development
of programmable electronic computers.
The basic idea of numerical weather prediction is to sample the
state of the fluid at a given time and use the equations of fluid
dynamics and thermodynamics to estimate the state of the fluid
at some time in the future.
Humans are required to interpret the model data into weather forecasts
that are understandable to the end user. Humans can use knowledge of
local effects which may be too small in size to be resolved by the model to
add information to the forecast. While increasing accuracy of forecast
models implies that humans may no longer be needed in the forecast
process at some point in the future, there is currently still a need for
human intervention.
Weather forecasting has direct applications in the following-
Severe weather alerts and advisories
Marine
Agriculture
Other commercial companies
Military applications
Air traffic control

9. 2-AEROSPACE AND AUTOMOBILE
INDUSTRY
Aerodynamics is a branch of Fluid dynamics concerned with studying
the motion of air, particularly when it interacts with a solid object, such as
an airplane, high speed bullet trains, racing cars etc. Aerodynamics is a
sub-field of fluid dynamics and gas dynamics,
and many aspects of aerodynamics theory are common to these fields.
Most of the early efforts in aerodynamics worked towards achieving
heavier-than air flight, which was first demonstrated by Wilbur and Orville
Wright in 1903. Since then, the use of aerodynamics
through mathematical analysis, empirical approximations, wind tunnel
experimentation, and computer simulations has formed the scientific
basis for ongoing developments in heavier-than-air flight and a number of
other technologies.
Understanding the motion of air around an object (often called a flow
field) enables the calculation of forces and moments acting on the object.
In many aerodynamics problems, the forces of interest are the
fundamental forces of flight: lift, drag, thrust, and weight. Of these, lift
and drag are aerodynamic forces, i.e. forces due to air flow over a solid
body.
As aircraft speed increased, designers began to encounter challenges
associated with air compressibility at speeds near or greater than the
speed of sound. The differences in air flows under these conditions led to
problems in aircraft control, increased drag due to shock waves, and
structural dangers due to aeroelastic flutter.
Stress distribution on fast moving train

10. Air flow pattern over the wings of an aircraft
3-TURBOMACHINES AND HYDRAULICS
Any devices that extract energy from or impart energy to a continuously
moving stream of fluid can be called a Turbomachine. Turbomachinery,
in mechanical engineering, describes machines that transfer energy
between a rotor and a fluid, including both turbines and compressors.
While a turbine transfers energy from a fluid to a rotor, compressor
transfers energy from a rotor to a fluid In general, the two kinds of
turbomachines encountered in practice are open and closed
turbomachines. Open machines such as propellers, windmills, and
unshrouded fans act on an infinite extent of fluid, whereas, closed
machines operate on a finite quantity of fluid as it passes through housing
or casing.
Turbomachines has direct applications in-
Power generation in thermal power plants, hydro power plants, wind
turbine
Jet Propulsion
Compressors, pumps and turbines in mechanical applications like
irrigation, HVACs systems, and sewage treatments plants.
Chemical and food processing industry
Hydraulics is a topic in applied science and engineering dealing with the
mechanical properties of liquids or fluids. At a very basic level, hydraulics
is the liquid version of pneumatics. Fluid mechanics provides the
theoretical foundation for hydraulics, which focuses on the engineering
uses of fluid properties. In fluid power, hydraulics are used for the
generation, control, and transmission of power by the use of pressurized
liquids. Hydraulic topics range through some part of science and most of
engineering modules, and cover concepts such as pipe flow, dam design,

11. fluidics and fluid control circuitry, pumps, turbines, hydropower,
computational fluid dynamics, flow measurement, river channel behavior
and erosion.

12. 4-FLUID AS COOLANT IN ENGINES,
ELECTRONICS, POWER PALNTS AND
MANUFACTURING
A coolant is a fluid which flows through or around a device to prevent its
overheating, transferring the heat produced by the device to other
devices that use or dissipate it. An ideal coolant has high thermal
capacity, low viscosity, is low-cost, non-toxic, and chemically inert, neither
causing nor promoting corrosion of the cooling system. Some applications
also require the coolant to be an electrical insulator. While the term
coolant is commonly used in automotive and HVAC applications, in
industrial processing, heat transfer fluid is one technical term more
often used, in high temperature as well as low temperature manufacturing
applications. Another industrial sense of the word covers cutting fluids.
Cooling effect can be achieved either through free or forced convection.
Some of the coolants with applications are-
The most common coolant is water. Its high heat capacity and low
cost makes it a suitable heat-transfer medium. It is usually used
with additives, like corrosion inhibitors and antifreeze.
Air is a common form of a coolant. Air cooling uses either
convective airflow (passive cooling), or a forced circulation using
fans (in electronics).
Hydrogen is used as a high-performance gaseous coolant. Its
thermal conductivity is higher than all other gases, it has high
specific heat capacity, low density and therefore low viscosity,
which is an advantage for rotary machines susceptible to windage
losses. Hydrogen-cooled turbogenerators are currently the most
common electrical generators in large power plants.
Inert gases are used as coolants in gas-cooled nuclear reactors.
Helium has a low tendency to absorb neutrons and become
radioactive.
Sulfur hexafluoride is used for cooling and insulating of some high-
voltage power systems Transformer oil is used for cooling and
additional electric insulation of high-power electric transformers.
Cutting fluid is a coolant that also serves as a lubricant for metal-
shaping machine tools. Oils are used for applications where water is
unsuitable. With higher boiling points than water, oils can be raised
to considerably higher temperatures (above 100 degrees Celsius)
without introducing high pressures within the container or loop
system in question. Mineral oils serve as both coolants and
lubricants.

13. NANOFLUIDS AS COOLANTS (RECENT DEVELOPMENT)
An emerging and new class of coolants is nanofluids which consist of a
carrier liquid, such as water, dispersed with tiny nano-scale particles
known as nanoparticles. Purpose-designed nanoparticles of e.g. CuO,
alumina titanium dioxide, carbon nanotubes, silica, or metals (e.g.
Copper, or silver nanorods) dispersed into the carrier liquid enhance the
heat transfer capabilities of the resulting coolant compared to the carrier
liquid alone. The enhancement
can be theoretically as high as 350%. The experiments however did not
prove so high thermal conductivity improvements, but found significant
increase of
the critical heat flux of the coolants. The particles form rough porous
surface on the cooled object, which encourages formation of new bubbles,
and their hydrophilic nature then helps pushing them away, hindering the
formation of the steam layer. Nanofluid with the concentration more than
5% acts like non-Newtonian fluids.
oSome significant improvements are achievable; e.g. silver nanorods
of 55±12 nm diameter and 12.8 μm average length at 0.5 vol.%
increased the thermal conductivity of water by 68%,.
o0.5 vol.% of silver nanorods increased thermal conductivity of
ethylene glycol based coolant by 98%.
oAlumina nanoparticles at 0.1% can increase the critical heat flux of
water by as much as 70%;
A nanofluid is a fluid containing nanometer-sized particles,called
nanoparticles. These fluids are engineered colloidal suspensions of
nanoparticles in a base fluid.
The nanoparticles used in nanofluids are typically made of metals, oxides,
carbides, or carbon nanotubes. Common base fluids include water,
ethylene glycol and oil.
Nanofluids have novel properties that make them potentially
useful in many applications in heat transfer, including microelectronics,
fuel cells, pharmaceutical processes, and hybrid-powered engines, engine
cooling/vehicle thermal management, domestic refrigerator, chiller, heat
exchanger, in grinding, machining and in boiler flue gas temperature
reduction. They exhibit enhanced thermal conductivity and the convective
heat transfer coefficient compared to the base fluid. Knowledge
of the rheological behavior of nanofluids is found to be very critical in
deciding their suitability for convective heat transfer applications

14. 5- PROCESS ENGINEERING, REFRIGERATION AND
HVAC SYSTEMS
Process Engineering focuses on the design, operation, control, and
optimization of chemical, physical, and biological processes. Process
engineering encompasses a vast range of industries, such as chemical,
petrochemical, agriculture, mineral processing, advanced material, food,
pharmaceutical, software development and biotechnological industries.
Several accomplishments have been made in Process Systems
Engineering-
Process design: synthesis of energy recovery networks, synthesis of
distillation systems (azeotropic), synthesis of reactor networks,
hierarchical decomposition flowsheets, design multiproduct batch plants.
Design of the production reactors for the production of plutonium, design
of nuclear submarines.
Process control: model predictive control, controllability measures, robust
control, nonlinear control, statistical process control, process monitoring,
thermodynamics-based control
Process operations: scheduling process networks, multiperiod planning
and optimization, data reconciliation, real-time optimization, flexibility
measures, fault diagnosis.
Refrigeration is a process of moving heat from one location to another
in controlled conditions. The work of heat transport is traditionally driven
by mechanical work, but can also be driven by heat, magnetism,
electricity, laser, or other means. Refrigeration has many applications,
including, but not limited to: household refrigerators, industrial freezers,
cryogenics, and air conditioning. The introduction of refrigeration allowed
for the hygienic handling and storage of perishables, and as such,
promoted output growth, consumption, and nutrition. The change in our
method of food preservation moved us away from salts to a more
manageable sodium level. Probably the most widely used current
applications of refrigeration are for air conditioning of private homes and
public buildings, and refrigerating foodstuffs in homes, restaurants and
large storage warehouses. The use of refrigerators in kitchens for storing
fruits and vegetables has allowed adding fresh salads to the modern diet
year round, and storing fish and meats safely for long periods.
HVAC(heating,ventilating, and air conditioning; also heating, ventilation,
and air conditioning)

is the technology of indoor and vehicular
environmental comfort. Its goal is to provide thermal comfort and
acceptable indoor air quality. HVAC system design is a sub-discipline of
mechanical engineering, based on the principles of thermodynamics, fluid
mechanics, and heat transfer. Refrigeration is sometimes added to the
field's abbreviation as HVAC&R or HVACR, (heating, ventilating and air-
conditioning & Refrigeration) or ventilating is dropped as in HACR (such as
the designation of HACR-rated circuit breakers).

15. HVAC is important in the design of medium to large industrial and office
buildings such as skyscrapers, on board vessels, and in marine
environments such as aquariums, where safe and healthy building
conditions are regulated with respect to temperature and humidity, using
fresh air from outdoors.

16. 6-RENEWABLE ENERGY SYSTEMS
BASED ON FLUID MECHANICS
Renewable energy resources and significant opportunities for energy
efficiency exist over wide geographical areas, in contrast to other energy
sources, which are concentrated in a limited number of countries. Rapid
deployment of renewable energy and energy efficiency, and technological
diversification of energy sources, would result in significant energy
security and economic benefits. It would also reduce
environmental pollution such as air pollution caused by burning of fossil
fuels and improve public health, reduce premature mortalities due to
pollution and save associated health costs.
A-WIND POWER
Wind energy or wind power is extracted from air flow using wind
turbines or sails to produce mechanical or electrical energy. Windmills are
used for their mechanical
power, windpumps for water pumping, and sails to propel ships. Wind
power as an alternative to fossil fuels, is plentiful, renewable, widely
distributed, clean, produces
no greenhouse gas emissions during operation, and uses little land. The
net effects on the environment are far less problematic than those of
nonrenewable power sources.
Wind farms consist of many individual wind turbines which are connected
to the electric power transmission network. Onshore wind is an
inexpensive source of electricity, competitive with or in many places
cheaper than coal or gas plants. Offshore wind is steadier and stronger
than on land, and offshore farms have less visual impact, but construction
and maintenance costs are considerably higher.
WIND POWER STATIONS IN XINJIANG, CHINA

17. As of 2014, Denmark has been generating around 40% of its electricity
from wind, and at least 83 other countries around the world are using
wind power to supply their electricity grids. Wind power capacity has
expanded to 369,553 MW by December 2014, and total wind energy
production is growing rapidly and has reached around 4% of worldwide
electricity usage. One of the biggest current challenges to wind power
grid integration is the necessity of developing new transmission lines to
carry power from wind farms, usually in remote lowly populated states in
the middle of the country due to availability of wind, to high load
locations, usually on the coasts where population density is higher. The
current transmission lines in remote locations were not designed for the
transport of large amounts of energy.
TURBINE DESIGN
Wind turbines are devices that convert the wind’s kinetic energy into
electrical power. The result of over a millennium of windmill development
and modern engineering, today’s wind turbines are manufactured in a
wide range of horizontal axis and vertical axis types. Arrays of large
turbines, known as wind farms, have become an increasingly important
source of renewable energy and are used in many countries as part of a
strategy to reduce their reliance on fossil fuels. Wind turbine design is the
process of defining the form and specifications of a wind turbine to extract
energy from the wind. A wind turbine installation consists of the necessary
systems needed to capture the wind’s energy, point the turbine into the
wind, convert mechanical rotation into electrical power, and other
systems to start, stop, and control the turbine. The aerodynamics of a
wind turbine is not straightforward. The air flow at the blades is not the
same as the airflow far away from the turbine. The very nature of the way
in which energy is extracted from the air also causes air to be deflected
by the turbine.
In addition the aerodynamics of a wind turbine at the rotor surface exhibit
phenomena that are rarely seen in other aerodynamic fields. The shape
and dimensions of the blades of the wind turbine are determined by the
aerodynamic performance required to efficiently extract energy from the
wind, and by the strength required to resist the forces on the blade

19. B- WAVE POWER
PELAMIS WAVE ENERGY CONVERTER ON SITE AT THE
EUROPEAN MARINE ENERGY CENTRE (EMEC), IN 2008
Wave power is the transport of energy by ocean surface waves, and the
capture of that energy to do useful work–for example, electricity
generation, water desalination, or
the pumping of water (into reservoirs). A machine able to exploit wave
power is generally known as a wave energy converter (WEC). Wave-
power generation is not currently a widely employed commercial
technology, although there have been attempts to use it. The major
competitor of wave power is offshore wind power, with more visual
impact.

20. 7-BIOMEDICAL APPLICATIONS
ARTIFICIAL HEARTS
An artificial heart is a device that replaces the heart. Artificial hearts are
typically used to bridge the time to heart transplantation, or to
permanently replace the heart
in case heart transplantation is impossible. An artificial heart is distinct
from a ventricular assist device designed to support a failing heart. It is
also distinct from a cardiopulmonary bypass machine, which is an external
device used to provide the functions of both the heart and lungs and are
only used for a few hours at a time, most commonly during cardiac
surgery.
In August 2006, an artificial heart was implanted into a 15-year-old girl at
the Stollery Children’s Hospital in Edmonton, Alberta. It was intended to
act as a temporary fixture until a donor heart could be found. Instead, the
artificial heart (called a Berlin Heart) allowed for natural processes to
occur and her heart healed on its own. After
146 days, the Berlin Heart was removed, and the girl’s heart was able to
function properly on its own
Patients who have some remaining heart function but who can no longer
live normally may be candidates for ventricular assist devices (VAD),
which do not replace the human heart but complement it by taking up
much of the function.
A centrifugal pump or an axial-flow pump can be used as an artificial
heart, resulting in the patient being alive without a pulse.
THE SYNCARDIA TEMPORARY TOTAL ARTIFICIALHEART

21. 8-SMART FLUIDS
A-MAGNETORHEOLOGICAL AND
ELECTRORHEOLOGICAL FLUIDS
A smart fluid is a fluid whose properties (for example the viscosity) can
be changed by applying an electric field or a magnetic field. The most
developed smart fluids today are fluids whose viscosity increases when a
magnetic field is applied. Small magnetic dipoles are suspended in a non-
magnetic fluid, and the applied magnetic field causes these small
magnets to line up and form strings that increase the viscosity. These
magnetorheological or MR fluids are being used in the suspension of the
automobile. Depending on road conditions, the damping fluid’s viscosity is
adjusted. This is more expensive than traditional systems, but it provides
better (faster) control.
Similar systems are being explored to reduce vibration in washing
machines, air conditioning compressors, rockets and satellites, and one
has even been installed in Japan’s National Museum of Emerging Science
and Innovation in Tokyo as an earthquake shock absorber.
Another major type of smart fluid are electrorheological or ER fluids,
whose resistance to flow can be quickly and dramatically altered by an
applied electric field (note, the yield stress point is altered rather than the
viscosity). Besides fast acting clutches, brakes, shock absorbers and
hydraulic valves, other, more esoteric, applications such as bulletproof
vests have been proposed for these fluids. Other applications include
brakes and seismic dampers, which are used in buildings in seismically-
active zones to damp the oscillations occurring in an earthquake.
Schematic of a magnetorheological fluid solidifying and
blocking a pipe in response to an external magnetic field.

22. MR fluid is different from a ferrofluid which has smaller particles. MR fluid
particles are primarily on the micrometre-scale and are too dense for
Brownian motion to keep them suspended Ferrofluid particles are
primarily nanoparticles that are suspended by Brownian motion and
generally will not settle under normal conditions. As a result, these two
fluids have very different applications.
B-FERROFLUID
A ferrofluid (portmanteau of ferromagnetic and fluid) is a liquid that
becomes strongly magnetized in the presence of a magnetic field.
Ferrofluid are colloidal liquids made of nanoscale ferromagnetic, or
ferrimagnetic, particles suspended in a carrier fluid (usually an organic
solvent or water). Each tiny particle is thoroughly coated with a surfactant
to inhibit clumping. Large ferromagnetic particles can be ripped out of the
homogeneous colloidal mixture, forming a separate clump of magnetic
dust when exposed to strong magnetic fields. The magnetic attraction of
nanoparticles is weak enough that the surfactant’s Van der Waals force is
sufficient to prevent magnetic clumping or agglomeration.
Ferrofluid was invented in 1963 by NASA’s Steve Papell as a liquid rocket
fuel that could be drawn toward a pump inlet in a weightless environment
by applying a magnetic field.
Ferrofluids can be made to self-assemble nanometer-scale needle-
like sharp tips under the influence of a magnetic field. When they
reach a critical thinness, the needles begin emitting jets that might
be used in the future as a thruster mechanism to propel small
satellites such as CubeSats.
Ferrofluids are used to form liquid seals around the spinning drive
shafts in hard disks. The rotating shaft is surrounded by magnets. A
small amount of ferrofluid, placed in the gap between the magnet
and the shaft, will be held in place by its attraction to the magnet.
The fluid of magnetic particles forms a barrier which prevents debris
from entering the interior of the hard drive.

23. MEDICAL APPLICATIONS
The first application is magnetic drug targeting. In this process the
drugs would be enclosed by a layer of ferrofluid in some way. The
combination would be injected into an area of the patient’s body
that required the drug treatment. The drugs would then be held in
the desired location by a magnetic field and allowed to act for a
time period (approximately 1 hour). The field would then be turned
off and the drugs would be allowed to disperse through the body.
This process would drastically decrease the necessary dose for a
treatment down to a level at which there would be no adverse side
effects once the drug is released from the magnetic field. The
motivation behind this type of treatment is for it to be used for
drugs with adverse side effects, i.e. chemotherapy.
The second application is an experimental cancer treatment called
targeted magnetic hyperthermia. This process takes advantage of
the ability of the nanoparticles to convert electromagnetic energy
into thermal energy or heat. Here, ferrofluid is injected into a target
tissue, usually a cancerous tumor. An oscillatory magnetic field is
focused on the location, allowing the ferrofluid to vibrate. The
vibration increases thermal energy at a frequency that does not
allow the surrounding water to heat up. The fluid can reach a
temperature that kills the desired cells without damaging
surrounding tissue.
The third application is for ferrofluid to be used to as an enhanced
contrast agent in magnetic resonance imaging (MRI). MRI images
depend on the difference in magnetic relaxation times of different
tissues to provide contrast. If biocompatible ferrofluids can be
selectively absorbed by some kind of tissue, then those tissues that
would not normally have high resolution would. Also, developing a
method for different tissues to uptake different amounts of ferrofluid
would give the tissues drastically different relaxation times, and
thus very sharp contrast and high resolution. This would allow very
good resolution of cancer cells.

24. 9- APPLICATIONS IN SPORTS
SHARK SKIN IN SWIM SUITS
Sharkskin is a smooth worsted fabric with a soft texture and a two-toned
woven appearance. Athletes in many competitive sports are using
technology to gain an advantage. In recent years, Fastskin fabric has been
developed by Speedo. This material allows the lowest-drag racing
swimwear in the world to be developed. The fabric mimics the rough
denticles of sharks’ skin to reduce drag in key areas of the body. (Shark
scales are tiny compared with those of most fishes and have a toothlike
structure, called dermal denticles—literally, “tiny skin teeth.” These
denticles are nature’s way of reducing drag on the shark.) Detailed design
of swimsuits was based on tests in a water flume and on computational
fluid dynamics (CFD) analyses. The same technology is now being used to
make outfits for athletes in Olympics. The fabric has been modified, based
on wind tunnel tests, to reduce drag based on the airflow direction unique
to sledding sports. The new outfits also eliminate most of the fabric
vibration (a major source of drag) found in other speed suits.
For both summer and winter sports, the ability to perform experimental
and theoretical fluid dynamics analysis and make design changes based
on these can make the difference in speed of several percent—the
difference between silver and gold!

25. 10-FORECASTING NATURAL DISASTERS
TROPICAL CYCLONE
A tropical cyclone is a rapidly rotating storm system characterized by
a low pressure center, strong winds, and a spiral arrangement
of thunderstorms that produce heavy rain. Depending on its location and
strength, a tropical cyclone is referred to by names such as hurricane
Tropical cyclones typically form over large bodies of relatively warm water.
They derive their energy through the evaporation of water from the ocean
surface, which ultimately recondenses into clouds and rain when moist air
rises and cools to saturation Tropical cyclones are typically between 100
and 2,000 km (62 and 1,243 mi) in diameter. Tropical cyclones out at sea
cause large waves, heavy rain, flood and high winds, disrupting
international shipping and, at times, causing shipwrecks. Tropical cyclones
stir up water, leaving a cool wake behind them, which causes the region
to be less favorable for subsequent tropical cyclones.
[38]
On land,
strong winds can damage or destroy vehicles, buildings, bridges, and
other outside objects, turning loose debris into deadly flying projectiles.
The storm surge, or the increase in sea level due to the cyclone, is
typically the worst effect from landfalling tropical cyclones, historically
resulting in 90% of tropical cyclone deaths. Over the past two centuries,
tropical cyclones have been responsible for the deaths of about 1.9 million
people worldwide. Large areas of standing water caused by flooding lead

26. to infection, as well as contributing to mosquito-borne illnesses. Crowded
evacuees in shelters increase the risk of disease propagation. Tropical
cyclones significantly interrupt infrastructure, leading to power outages,
bridge destruction, and the hampering of reconstruction efforts.
Because of the forces that affect tropical cyclone tracks, accurate track
predictions depend on determining the position and strength of high- and
low-pressure areas, and predicting how those areas will change during the
life of a tropical system. The deep layer mean flow, or average wind
through the depth of the troposphere, is considered the best tool in
determining track direction and speed. If storms are significantly sheared,
use of wind speed measurements at a lower altitude, such as at the
70 kPa pressure surface (3,000 meters or 9,800 feet above sea level) will
produce better prediction High-speed computers and sophisticated
simulation software allow forecasters to produce computer models that
predict tropical cyclone tracks based on the future position and strength
of high- and low-pressure systems. Combining forecast models with
increased understanding of the forces that act on tropical cyclones, as
well as with a wealth of data from Earth-orbiting satellites and other
sensors, scientists have increased the accuracy of track forecasts over
recent decades.
Other applications include-
Design of flood control systems
Containing oil spills in sea
Sewage and water treatment

27. 11-MEMS
An exciting new area in fluid mechanics is microfluidics, applied to
microelectromechanical systems (MEMS—the technology of very small
devices, generally ranging in size from a micrometer to a millimeter).
Alan Epstein, a professor of aeronautics and astronautics at the
Massachusetts Institute of Technology, and his team have done a lot of
research on tiny gasturbine
engines made of silicon. They are about the size of a quarter (as shown in
the figure) and can be easily mass produced. Unlike conventional large
turbines that are assembled from many components, these turbines are
built basically from a solid piece of silicon. Professor Epstein discovered
that the basic concepts of turbine theory apply even to his microturbines;
the fluid mechanics turns out to be the same as that for larger engines, as
long as the passages made for gas flow are larger than about 1 μm in
diameter (smaller than this and non continuum molecular kinetics is
needed). The rotor and its airfoils are carved out of a single wafer, as
shown in the figure. Additional “plumbing” and bearings are etched onto
the wafers that are to sandwich the rotor. Combustion occurs just outside
the rotor, at the same wafer level, spinning it by pushing on its airfoils
from the outside. At more than a million rpm, these turbines make no
audible noise Electricity will then be generated
using, for example, a tiny generator. The fuel source could be packaged
with the engine or come as a replaceable cartridge like a cigarette lighter.
In terms of
power density, the little engine will easily beat batteries,
with an output of somewhere between 50 and 100 watts!
In particular, a lot of research is being done in “lab-on-a-chip” technology,
which has many applications. An example of this is in medicine, with
devices for use in the immediate point-of care diagnosis of diseases, such
as real-time detection of bacteria, viruses, and cancers in the human
body. In the area of security, there are devices that continuously sample
and test air or water samples for biochemical toxins and other dangerous
pathogen.

28. REFRENCES
1-WIKIPEDIA
2-NPTEL
3-INTRODUCTION TO FLUID MECHANICS, FOX AND MCDONALDS
4-FLUID MECHANICS FUNDAMENTALS AND APPLICATIONS Y.A. CENGEL