Fluid Mechanics

Fluid Mechanics, one in every of the oldest branches of Physics and thence the inspiration for the understanding of the {various the many} various aspects of the applied sciences and engineering, issues itself with the investigation of the motion and equilibrium of fluids. It’s widespread interest in most fields of engineering also as in astronomy, biology, biomedicine, metrology, chemical science, plasma physics and geophysical science. The frontier of fluid dynamic analysis has been extended in to the exotic regimes of of hyper speed flight and flow of electrically conducting fluids.

Anything that occupies space might be a matter. Matter is come apart into three states solid, liquid and gas. The matters have defined shape in a given thermodynamic condition and in the absence of external force are called solids. A substance that has no fixed shape and yields easily to external pressure; a gas or (especially) a liquid.The properties of fluids unit of measurement of general importance to the study of mechanics.
Density=Massunit volume specific weight =weightunit volume specific volume =Volumemass specific gravity =density of objective density of water
Fluid Dynamics
Fluid Dynamics is that the study of the properties and behaviour of moving fluids or fluid flow. Fluid Dynamics is sub-discipline of fluid mechanics that deals with fluid flow i.e. the branch of knowledge of fluids (liquids and gases) in motion. it’s several sub disciplines itself, beside the study of air and completely different gases in motion and hydraulics (the study of liquids in motion). Fluid dynamics options a good choice of applications, beside hard forces and moments on craft, crucial the mass rate of flow of oil through pipelines, predicting weather patterns, understanding nebulae partly and reportedly modelling fission weapon detonation. a quantity of its principles area unit even utilized in traffic engineering, where traffic is treated as never-ending fluid.

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1.3 Heat transfer
Heat transfer can defined the transmission of energy from one region to a different as results of temperature difference between them.
Modes of Heat transfer:
Conduction, Convection and Radiation.

1.3.1 Conduction:
Conduction is the go with the flow of heat in a substance due to deal of energy among molecules having more energy and molecules having low energy.

1.3.2 Convection:
The transfer of energy from one place to any other because of macroscopic motion in a fluid, added on to the energy transfer by conduction is called heat transfer by convection.

Classification of Convection heat transfer
1. Free (or) Natural convection heat transfer
2 .Forced convection heat transfer
Free(or) Natural convection heat transfer:
Fluid motion occurs due to density variation caused by temperature differences.

Forced convection heat transfer:
Fluid movement because of an external agency.

1.3.3 Radiation:
All physical substance emits thermal radiation in the form of electromagnetic waves due to irrational and rotational moves of the molecules and atoms which make up the substance.

Characteristics of radiation
1. Rate of emission increases with temperature level.

2. No material medium required for electricity transfer to occur.

1.4 Magneto hydrodynamics (MHD)
Magneto hydrodynamics is the multi-disciplinary study of the flow of electrically conducting fluids in electromagnetic fields.

Examples of such fluids embrace plasmas, liquid metals, and salt water. The fluid flow equations square measure resolved at the same time with differential equation of electromagnetism. We can describe scientifically the interaction of magnetic attraction fields and fluids by the right application of the principles of the specialtheory of scientific theory. The sensible applications of those principles, in Physical engineering, astronomy, geophysical science etc., became necessary in recent years. The study of applications to time is understood as magneto electric machine fluid mechanics or magneto electric machine fluid dynamics.

The study of Magneto hydrodynamics (MHD) plays an important role in agriculture, engineering and petroleum industries. MHD has won practical applications, for instance, it may be used to deal with problems such as cooling of nuclear reactors by liquid sodium and induction flow water which depends on the potential differencing the fluid direction perpendicular to the motion and goes to the magnetic field. Today the magneto hydrodynamics has many recognized applications in Science and Industry. To name a few, namely Geophysics, Cosmic physics, controlled thermonuclear fusion and direct energy conservations are some of these areas where MHD plays an important role. The application of electromagnetic fields in controlling the heat transfer in aerodynamic heating lead to the study of magneto hydrodynamic heat transfer. This MHD heat transfer has gained significance owning to recent advancement of space technology. The MHD heat transfer can be divided into two sections. One contains problems in which heating is an incidental bi-product of the electromagnetic fields as in magneto hydrodynamic (MHD) generators, pumps etc. The second consists of problems in which the primary use of electromagnetic fields is to control heat transfer. Liquid in the geothermal region is an electrically conducting liquid because of high temperature. Hence the study of the interaction of the geomagnetic field with the fluid in the geothermal region is of great interest, thus leading to the study of magneto hydrodynamic (MHD) convection flow through a porous medium.

1.5 Heat flux
Heat flux or thermal flux is that the rate of heat energy transfer through a given surface. Heat flux is that the heat rate per unit space. The SI derived unit of heat rate is joule per second, or watt. 
1.6 Porouse Medimum
A porous medium consists of pores between some particulate part, contained at intervals a vessel, or some management volume.A porous medium (or a porous material) may be a material containing pores (voids). The skeletal portion of the fabric is usually referred to as the “matrix” or “frame”. The pores area unit usually crammed with a fluid (liquid or gas). different properties of the medium (e.g., porousness, durability and electrical conductivity).The thought of porous media is employed in several areas of subject area and engineering: filtration, mechanics (acoustics, geomechanics, soil mechanics and rock mechanics), engineering (petroleum engineering, bio-remediation and construction engineering) and geosciences. Fluid flow through porous media may be a subject of commonest interest and has emerged a separate field of study. The study of a lot of general behavior of porous media involving deformation of the solid frame is named Poromechanics.

1.7 Steady and Unsteady flow
When all the time derivatives of a flow field vanish, the flow is considered to be a steady flow. Steady-state flow refers to the condition where the fluid properties at a point in the system do not change over time. Otherwise, flow is called unsteady. Whether a particular flow is steady or unsteady, can depend on the chosen frame of reference. For instance, laminar flow over a sphere is steady in the frame of reference that is stationary with respect to the sphere. In a frame of reference that is stationary with respect to a background flow, then the flow is unsteady.

1.8 Compressible and incompressible flow
All fluids area measure compressible to some extent, that is, changes in pressure or temperature can end in changes in density. However, in several things the changes in pressure and temperature area measure sufficiently small that the changes in density area measure negligible. For this case the flow as an incompressible flow. Otherwise compressible flow equations should be used.

1.9 Uniform and Nom-Uniform FlowsA flow during which the velocities area unit same in each magnitude and direction from reason to reason. Uniform flow is feasible only in a very channel of constant cross section and gradient.

Important points:
1. For a non-uniform flow, the changes with point may be determined either within the direction with the flow or in direction perpendicular to it.

2. Non-uniformity in a course perpendicular to the flow is always encountered close to solid limitations past which the fluid flows.

Reason: All fluids possess viscosity which reduces the relative velocity (of the fluid w.r.t. to the wall) to zero at a solid boundary. This is called no-slip condition.

1.10 Newtonian fluid and Non -Newtonian fluid
Fluid for which the shearing stress is directly proportional to charge of shearing strain are designated as Newtonian fluid.

Fluid for which the shearing stress is not linearly related of shearing pressure are designated as Non- Newtonian fluid
1.11 Laminar flow (streamline flow)Laminar flow, typically referred to as flow, happens once a fluid flows in parallel layers, with no disruption between the layers.

1.12 Soret Effect
When heat and mass transfer occur simultaneously in a moving fluid, the relations between the fluxes and the dividing potentials are of more intricate nature. Mass fluxes can be created by temperature gradients and this is the soret effect or thermo –diffusion effect. The soret effect dramatically lowers the thermal convection threshold, since the concentration gradients release much more slowly than temperature gradients due to the disparate values of the mass diffusion coefficient and the thermal diffusion.1.13 ViscosityViscosity may be a live of the resistance of a fluid that is being malformed by either shear stress or tensile stress. In everyday terms (and for fluids only), consistence is “thickness” or “internal friction”. Thus, water is “thin”, having a lower consistence, whereas honey is “thick”, having the next consistence. Put simply, the less viscous the fluid is, the larger its simple movement (fluidity). 
1.14 Suction
Suction is that the flow of a fluid into a partial vacuum, or region of depression. Thepressure gradient between this region and therefore the close pressure can propel matter toward the depression space. Suction is popularly thought of as a horny impact that is inaccurate since vacuums don’t innately attract matter. 
1.15 Stress
In continuum mechanics, pressure is a degree of the inner forces performing inside a deformable frame. Quantitatively, its a degree of the common force according to unit place of a surface inside the body on which internal forces act.

1.16 Magnetic Field
A magnetic field can be represented by means of a mathematical description of the magnetic impact of electric currents and magnetic materials. The magnetic subject at any given factor is exact by way of both a course and a value (or strength); as such it’s far a vector field.