APPLICATIONSOF FLUID

MECHANICS 

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 ApproachB-Lagrangian versus Eulerian Approach

5-BRIEF HISTORY

6- SCOPE OF FLUID MECHANICS

PART-B

AREAS OF APPLICATION OF FLUIDMECHANICS

1-METEOROLOGY (WEATHER FORECASTING)

2-AEROSPACE AND AUTOMOBILE INDUSTRY

3-TURBOMACHINES AND HYDRAULICS

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 ANDELECTRORHEOLOGICAL FLUIDS

B-FERROFLUIDMEDICAL APPLICATIONS

9- APPLICATIONS IN SPORTS

SHARK SKIN IN SWIM SUITS

10-FORECASTING NATURAL DISASTERS

TROPICAL CYCLONE

11-MEMS

PART-A

INTRODUCTION TO FLUIDMECHANICS

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 madeout 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 ashear (tangential) stress no matter how small the shear stress may be. Fluids tend to flow when we interact with them while solids tend to deformor bend. We can also define a fluid as any substance that cannot sustain ashear stress when at rest.

2-DIFFERENCE IN BEHAVIOUR OF FLUID ANDSOLID

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 basiclaws governing the fluid motion. The basic laws, which are applicable to any fluid, are-1. The conservation of mass2. Newton’s second law of motion3. The principle of angular momentum4. The first law of thermodynamics5. The second law of thermodynamics

4-DIFFERENT APPROACHES IN STUDY OF FLUIDMECHANICS

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; solutionof 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.

5-BRIEF HISTORY

SCIENTISTS/ENGINEERS CONTRIBUTIONARCHIMEDES FLUID STATICSLEONARDO DA VINCI FLUID STATICS(OBSERVATIONS AND

EXPERIMENTS)TORICELLI INVENTED THE BAROMETERISSAC NEWTON INVESTIGATED VISCOSITYBLAISE PASCAL HYDROSTATICSBERNOULLI HYDRODYNAMICSLEONARD EULER, R D ALEMBERT, J LLAGRANGE, 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, pipingsystems needed in chemical plants; the aerodynamics of automobiles andsub- 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.

PART-B

AREAS OF APPLICATION OF FLUIDMECHANICS

1-METEOROLOGY (WEATHERFORECASTING)

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 stateof 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.

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, Englishscientist Lewis Fry Richardson published “Weather Prediction By NumericalProcess”,The first computerized weather forecast was performed by a team led by the mathematicianJohn 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 toadd 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

2-AEROSPACE AND AUTOMOBILEINDUSTRY

Aerodynamics is a branch of Fluid dynamics concerned with studying the motion of air, particularly when it interacts with a solid object, such asan 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 aerodynamicsthrough 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

Air flow pattern over the wings of an aircraft

3-TURBOMACHINES AND HYDRAULICSAny 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 housingor casing.

Turbomachines has direct applications in-

Power generation in thermal power plants, hydro power plants, windturbine

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,

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

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, neithercausing 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 manufacturingapplications. 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.

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 enhancementcan be theoretically as high as 350%. The experiments however did not prove so high thermal conductivity improvements, but found significant increase ofthe 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.

o Some 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%,.

o 0.5 vol.% of silver nanorods increased thermal conductivity of ethylene glycol based coolant by 98%.

o Alumina 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 potentiallyuseful 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 convectiveheat transfer coefficient compared to the base fluid. Knowledgeof the rheological behavior of nanofluids is found to be very critical in deciding their suitability for convective heat transfer applications

5- PROCESS ENGINEERING, REFRIGERATION ANDHVAC 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 controlProcess 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, fluidmechanics, 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 asthe designation of HACR-rated circuit breakers).

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.

6-RENEWABLE ENERGY SYSTEMSBASED 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 technologicaldiversification 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 areused for their mechanicalpower, windpumps for water pumping, and sails to propel ships. Wind power as an alternative to fossil fuels, is plentiful, renewable, widely distributed, clean, producesno 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 constructionand maintenance costs are considerably higher.

WIND POWER STATIONS IN XINJIANG, CHINA

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 extractenergy from the wind. A wind turbine installation consists of the necessarysystems 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

B- WAVE POWER

PELAMIS WAVE ENERGY CONVERTER ON SITE AT THEEUROPEAN 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, orthe 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.

7-BIOMEDICAL APPLICATIONS

ARTIFICIAL HEARTS

An artificial heart is a device that replaces the heart. Artificial hearts aretypically used to bridge the time to heart transplantation, or to permanently replace the heartin 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 externaldevice 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. After146 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

8-SMART FLUIDS

A-MAGNETORHEOLOGICAL ANDELECTRORHEOLOGICAL 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 smallmagnets 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 isadjusted. 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.

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 twofluids 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 surfactantto inhibit clumping. Large ferromagnetic particles can be ripped out of thehomogeneous 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 debrisfrom entering the interior of the hard drive.

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 ferrofluidwould give the tissues drastically different relaxation times, and thus very sharp contrast and high resolution. This would allow very good resolution of cancer cells.

9- APPLICATIONS IN SPORTS

SHARK SKIN IN SWIM SUITS

Sharkskin is a smooth worsted fabric with a soft texture and a two-tonedwoven appearance. Athletes in many competitive sports are using technology to gain an advantage. In recent years, Fastskin fabric has beendeveloped 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 designof swimsuits was based on tests in a water flume and on computational fluid dynamics (CFD) analyses. The same technology is now being used tomake outfits for athletes in Olympics. The fabric has been modified, basedon 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!

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 oceansurface, which ultimately recondenses into clouds and rain when moist airrises 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 cyclonesstir 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 millionpeople worldwide. Large areas of standing water caused by flooding lead

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 thelife 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

11-MEMSAn 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 gasturbineengines 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, aslong 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 generatedusing, 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 ofpower 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.

REFRENCES

1-WIKIPEDIA

2-NPTEL

3-INTRODUCTION TO FLUID MECHANICS, FOX AND MCDONALDS

4-FLUID MECHANICS FUNDAMENTALS AND APPLICATIONS Y.A. CENGEL