Introduction
Mechanics is a branch of physical science that deals with moving and stationary bodies influenced by forces. It is divided into two branches called dynamics and statics. Dynamics deals with moving bodies while statics deals resting bodies
Mechanics also has a subcategory called fluid mechanics. Fluid mechanics is the science concerning the behavior of fluids. It could be fluid statics when it tackles about the body at rest. On the other hand, it could be fluid dynamics when the fluid body being studied is in motion.
Fluid mechanics is a study regarding the behavior of material that can bend and reshape unrestrictedly with the control of shearing forces. The shearing force deforms a fluid even in small amounts; however, the deformation velocity will be likewise little .
Fluid mechanics also include the study of interactions between fluids with solids or fluid with other fluids at the borders. Fluid mechanics however, can be termed as fluid dynamics as well when fluids under consideration are at rest in an exceptional instance of movement having no velocity .
A fluid is defined by the property of deformation ability, and the shearing forces essential for the deformation of a fluid body becomes zero when the deformation velocity becomes zero as well. In contrast, a solid body behaves in such a way that the deformation and not the deformation velocity approaches zero as the forces required deforming it approaches zero. For solids, the stress is relative to strain. For fluids, stress is relative to strain rate .
Substances can exist as solid, liquid or gas. These three are the fundamental phases of matter. When subjected to extreme temperatures, matter can also exists as plasma. On the other hand, a matter or any substance that exist between the boundary of the liquid state and the gas phase is referred to as fluid. Fluid is distinguished by its ability to resist a given shear force. The shear force is a tangential stress that enforces changes to a substance’s shape. Fluid’s behavior is different from solid. Upon the application of shear stress, fluids deform incessantly whether the stress is big or small, whereas solids resist the shear stress applied by deforming .
There are several categories of fluid mechanics. Hydrodynamics is the study of the fluid motion that is almost incompressible. These incompressible fluids are gases at low speed and liquids mainly water. Hydraulics is a subcategory of hydrodynamics. It deals with liquid flows in open channels and pipes.
Gas dynamics is concerned with the flow of fluids that go through momentous density adjustments, for instance, the gases flow at high speed through nozzles. Aerodynamics is also concerned with the gas flow over bodies like rockets, aircraft and vehicles at low or high speeds. Fluid dynamics are also involved in oceanography, hydrology and meteorology and natural flows .
Fluids such as gases and liquids (air and water) are very prevalent in our daily life. Fluid mechanics is involved in flow in channels and a pipe, flow of blood and air in our body, Drag or air resistance, wind loading, projectile motion, shock waves and jets, combustion, sedimentation, irrigation, oceanography and meteorology. Since fluid mechanics is very vital in our living, this paper focuses on the uses of fluid mechanics.
Uses
Fluid mechanics is employed in designing of water supply system, waste water treatment, shock absorbers, dam spillways, valves, flow meters, automatic transmissions, ships, submarines, breakwaters, brakes, marinas, aircrafts, rockets, computer disk drives, windmills, turbines, pumps, HVAC systems, bearings and artificial organs .
Fluid mechanics is also present in sports items application such as in golf balls, surf boards, yatchs, hang gliders and race cars.
Uses: Hydrodynamic Design Concerning Cavitation
Cavitation is the ripping apart of a fluid-solid or liquid interface. It happens due to the decrease on the local static pressure created through the dynamic movement of the fluid in the borers or internal part of a liquid body. The rupture in cavitation is the development of an observable bubble. Microscopic voids are present in liquids like water. These voids serve as cavitation nuclei. When the cavitation nuclei develop into a visible size, cavitation happens. This occurrence is similar to boiling but cavitation is separated from this phenomenon because boiling involves an increase in temperature and not decrease in pressure.
Some applications of cavitation are etchers, cutters and ultrasonic cleaners. When cavitation bubbles come into areas of towering pressure and then collapse, sonoluminescence takes place. This is the phenomena when the underwater shock waves produce small quantity of light .
Body cavitation is a form of cavitation wherein the body is a representation of the surface ship’s bulbulous bow section. Body cavitation is created in such a way wherein inside it is a spherical-shaped ranging/sonar system and sound navigation system. Due to its shape, it is termed as the sonar dome .
When the ship’s velocity is high, the sonar domes begin to cavitate. Cavitation creates noise that makes sonar systems ineffectual. Consequently, many fluid dynamicists and naval architects try to create a dome that does not cavitate. They uses the model-scale evaluation that let the engineers assess immediately if the created dome is significantly improved in terms of cavitation performance .
The model scale evaluation is done in water tunnels. It requires an environment with enough nuclei to represent the operation conditions of the prototypes. Liquid tension or the nuclei distribution must be guaranteed to be in minimum level (Lauchle, Billet & Deutsch, 1989).
Engineers utilize different variables in which the body works such as temperature, gas content level and hydrostatic pressure. Concepts of fluid dynamic are applied to create a good hydrodynamic design.
Fluidic Actuators
Fluidic actuators are equipment that employs fluid logic circuits in order to generate a pressure perturbations or oscillatory velocity in shear layers and jets. They are significant for improving mixing, postponing separation and containing noise. Fluidic actuators can be applied in controlling shear flow. Actuators can function in extreme thermal conditions; they do not have moving parts; they can create controllable perturbations in terms of phase, amplitude and frequency; they are not vulnerable to electromagnetic interference; and they are simple to incorporate into a running apparatus.
Current progress in microfabrication and miniaturization in fluidics technology made them convenient to utilize. The fluidic actuator generates an oscillatory flow that is self-maintaining through the concepts of backflow and wall attachment that happen inside the miniature channels of the apparatus. Fluidic thrust vectoring can improve maneuverability. It can be done without the presence of additional surfaces close to the nozzle exhaust. This concept serves a significant role in designing aircrafts (Raman, Raghu & Bencic, 1999).
Reduction of Drag
It is important to reduce drag because it can result to the reduction of operation costs, fuel weight and increase in automobile payload and range. Drag is present in naval surface vehicles, air vehicles and undersea vehicles.
Experiments show that fifteen to twenty-five percent reductions are feasible through proper sublayer structure control. The development of dense and huge arrays of microactuators is desired to control the said structures in order to attain a practical reduction needed in hydronautical and aeronautical vehicles. The actuators spontaneously relocate a preset capacity of fluid among the walls and the thick sublayer in such a way that cancels out the product of the sublayer vortices .
Electrokinetic flow gives a method to shift little quantity of fluid in extremely little apparatus on a highs-peed time level. A scheme of architecture derived from independent unit cells supplies significantly reduced processing management requirements inside individual unit cells. The unit cells consist of a comparatively little quantity of individual actuators and sensors. Development of a full-scale electrokinetic microactuator using fundamental concepts of scaling principles will be practical for meeting demands for dynamic control of sublayers of vehicles.
Rotary Fuel Atomizer
The exceedingly elevated rotation velocity (approximately 100,000 rpm) at which undersized gas turbine engines work frequently permits rotary centrifugal atomizers to generate liquid fuel spray. The fuel spray is produced in the combustor.
Drop sizes are based on fluid properties, such as gas and liquid densities, the viscosities as well as the gas-liquid surface tension.
Acceleration causes the fuel to flow into the channels in order to create a liquid film on the canal walls. The great acceleration result to a common film thickness of merely around 10 mm. To generate a good performance of atomization, the channel shape is selected. Each shape result to drop sizes based on cross-flow velocity. Dimensionless groups such as viscosity ratios and gas-liquid density determine the performance of atomization .
Conclusion
Fluid Mechanics is the study of fluid behavior. Fluids are materials that can be bent and reshaped without limit through the influence of shearing forces. The shearing force deforms a fluid even it is in small amount. The stress applied on fluids is relative to the strain rate and the strain amount alone. The deformation depends on the strength of the shearing force.
Since fluids are part of our daily life, studying its behavior is very important.
Fluid Mechanics has universal uses. It is important on the study of climate and weather, combustion, aerodynamics, energy generation, coastal and ocean engineering, hydrology and hydraulics, geology, sports and recreation and water resources. In this paper, uses of fluid mechanics were shown through the discussion of cavitation, fluidic actuators, reduction of drag and rotary fuel atomizer.
References
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