# Fluids mechanics class 1 -Module 1

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### Fluids mechanics class 1 -Module 1

• 1. FLUIDS MECHANICS CIVIL ENGINEERING
• 2. ABDUL MUJEEB A S S I S TA N T P R O F E S S O R K V G C E , S U L L I A FLUIDS MECHANICS
• 3. What is FLUID??  The substance that is capable of flowing under an applied shear stress
• 4. What is matter??  Matter is any substance or material that occupies space and has mass  Different States/Phases of matter are….??  1. Solid  2. Liquid  3. Gas Fluid
• 5. Mechanics??  Study concerned with motion  Study of motion of fluid is called………….
• 6. Examples for fluid  All liquid and Gases
• 7. WHY
• 8. WHY
• 9. WHY
• 10. Non Newtonian Fluid
• 11. COURSE OUTCOMES C303.1. Understand the basic properties of fluids like mass density, specific weight, specific gravity, specific volume, viscosity, cohesion, adhesion, surface tension, capillarity, vapour pressure of liquid, compressibility and bulk modulus, pressure inside a water droplet, pressure inside a soap bubble and liquid jet and apply Newton's law of viscosity in solving practical problems related to fluid properties.
• 12. PASCAL’S LAW AND APPLICATIONS
• 13. PASCAL’S LAW AND APPLICATIONS
• 15. COURSE OUTCOMES C303.2. Apply the principles of Pascal's law and hydrostatic law for computations of pressure in fluid using simple, differential & inclined manometers.
• 16. Forces on Different Surfaces in contact with fluid
• 17. On Dam
• 18. On Lock Gates
• 19. COURSE OUTCOMES C303.3.Understand the significance of basic principles of fluid statics and application of hydrostatic law in determining forces on horizontal, vertical and inclined and curved surfaces and hydraulic structures like dam and lock gates
• 20. Fluid Kinematics
• 21. COURSE OUTCOMES C303.4.Understand the principles of kinematics with specific emphasis on application of three-dimensional continuity equation in Cartesian coordinate system, stream function, velocity potential, orthogonality of streamlines and equipotential lines for rotational and irrotational motion of fluid
• 22. Bernoulli's Principle
• 23. Application in Orifice and Mouthpiece
• 24. Venturimeter
• 25. Pipe Bends
• 26. Notches and Weirs
• 27. COURSE OUTCOMES C303.5. Apply the principles of Bernoulli's equation in measurement of discharge through horizontal Venturimeter, orifice meter, pitot tube and apply momentum equation in pipe bend and also to determine discharge through notches and weirs such as rectangular, triangular, trapezoidal, Cippoletti, broad crested and submerged weirs
• 28. Losses due to friction
• 29. Pipe in series and Parallel and Design of pipe network
• 30. Pipe Network
• 31. Sudden and Gradual Closure of valve
• 32. COURSE OUTCOMES C303.6. Apply fundamental concepts of fluid mechanics in solving fluid flow problems in pipes connected in parallel and series, head losses in pipe due to friction and sudden expansion, design of pipe and analysis of pipe networks by Hardy cross method and also to study the effect of water hammer due to sudden and gradual closure of rigid and elastic valve.
• 33. UNITS Write the suitable physical units for the following quantities: 1. Length =-------------- 2. Mass =---------------- 3. Time =---------------- 4. Area =---------------- 5. Volume=-------------- 6. Velocity=-------------- 7. Angular velocity=--------------- 8. Acceleration=------------------- 9. Angular acceleration=----------------- 10. Discharge=---------------- 11. Acceleration due to gravity=--------------- 12. Kinematic viscosity=-----------------
• 34. UNITS 13. Force=----------------- 14. Weight=---------------- 15. Density=-------------------- 16. Surface tension=------------ 17. Work, Energy=---------------- 18. Power=---------------------- 19. Torque=--------------------- 20 Momentum=--------------------
• 35. MODULE 1 FLUIDS AND ITS PROPERTIES INTRODUCTION:  Fluids mechanics is that branch of science which deals with the behavior of fluids ( liquids or gases) at rest as well as in motion.  Thus this branch of science deals with statics, kinematics and dynamic aspects of fluids.  The study of fluids at rest is called as fluids statics  The study of fluids at motion, where pressure forces are not considered, then the study is called as fluids kinematics.  The study of fluids at motion, where pressure forces are considered , then the study is called as fluids dynamics.
• 36. PROPERTIES OF FLUIDS  Density or Mass density:  Density or mass density of a fluid is defined as the ratio of the mass of a fluid to its volume.  Thus mass per unit volume of a fluid is called mass density.  It is denoted by the symbol “ρ” (rho).  The unit of mass density in SI unit is kg per cubic meter (kg/m3)  The value of density of water is 1000 kg per cubic meter.  Specific weight or weight density:  Specific weight or weight density of a fluid is the ratio between the weight of a fluid to its volume. Thus weight per unit volume of a fluid is called weight density.  It is denoted by the symbol “w”.  The specific weight or weight density of water is 1000*9.81 N per cubic meter.  SI uni t of weight density is N/m3
• 37.  Specific volume:  It is defined as the volume of a fluid occupied by a unit mass.  Or, volume per unit mass of a fluid is called specific volume. Specific gravity:  Specific gravity is defined as the ratio of the weight density or density of a fluid to the weight density or density of a standard fluid.  For liquids, the standard fluid is taken water and for gasses, standard fluid is taken air.  Specific gravity is also called as relative density.  It is dimensionless quantity and is denoted by S.  Numerical Problems………………
• 39. Viscosity:  Viscosity is defined as the property of a fluid which offers resistance to the movement of one layer of fluid over another adjacent layer of a fluid.  When two layers of a fluid, a distance ‘dy’ apart, move one over the other at different velocities, say ‘u’ and ‘u+du’, the viscosity together with relative velocity causes shear stress acting between the fluid layers.  The top layer causes a shear stress on the adjacent lower layer, while the lower layer causes a shear stress on the adjacent top layer. This shear stress is proportional to the rate of change of velocity with respect to y. It is denoted by symbol τ (tau).
• 41.  Unit of Dinemic viscosity………………….
• 44.  Unit of Kinematic viscosity………………….
• 47. Newtonian and Non Newtonian fluid  The fluids that obey this law is called Newtonian fluid and that not obey are called Non Newtonian fluid.
• 48. Why water forms droplets
• 49. ADHESION  It is intermolecular attractive force between molecules of different kind or phase
• 50. COHESION  It is intermolecular attractive force between molecules of same kind or same phase
• 51. Adhesion and Cohesion: Water on Pine Needles
• 55. Surface Tension  Tensile force acting on a surface of a liquid in contact with gas or on surface between two immiscible liquids such that contact surface behaves like membrane under tension.  It is denoted by σ (sigma).  Unit is N/m
• 56.  All the molecules on free surface experience downward force.  Thus very thin film is formed at surface due to inward molecular pull. (ie due to tension on free surface)
• 58. Surface tension on liquid droplet  Liquid droplets tend to assume a spherical shape since a sphere has the smallest surface area per unit volume.  The pressure inside a drop of fluid can be calculated using a free-body diagram of a spherical shape which is cut in to two halves of radius r.  Let σ = surface tension of the liquid p= Pressure intensity inside the droplet d= diameter of droplet
• 60.  The force acting on one half will be (i) Tensile force due to surface tension acting around circumference of cut portion. i.e.= σ x circumference = σ x Πd (ii) Pressure force on area = p X (𝜋/4)𝑑2 At equilibrium, these two forces will be equal and opposite p x (𝜋/4)𝑑2= σ x Πd The above equation show that with increase in diameter of droplet, pressure intensity decreases p= 4σ 𝑑
• 61. Surface tension on a hollow bubble or soap bubble
• 62. Surface tension on a liquid jet:
• 63. What happens if bread is dipped in tea? Why?
• 64. After few minutes….!!!
• 65. Capillarity  Capillarity is a phenomenon of rise or fall of liquid surface relative to the adjacent general level of liquid when the tube is held vertically in liquid.  This phenomenon is due to the combined effect of cohesion and adhesion of liquid particle.  The rise of liquid level is known as capillary rise whereas the fall of liquid surface is known as capillary depression.It is expressed in terms of cm or mm of liquid.  Armchair Animation Capillary Action.mp4  Capillary action is the ability of a liquid to flow in narrow spaces without the assistan.mp4
• 66. The magnitude of capillarity is dependent upon  Diameter of tube.  Specific weight of liquid.  Surface tension of liquid.
• 67. Expression for Capillary rise Consider a glass tube of diameter ‘d’ opened at both ends and is inserted in liquid. The liquid will rise in tube above the level of liquid. Let h= Height of liquid in tube. θ= the contact angle between liquid and glass tube. σ= surface tension of liquid. At equilibrium, weight of liquid on height ‘h’ is balanced by force at the surface of liquid in tube. This force is surface tension
• 68.  The weight of the liquid column of height ‘h’ in the tube = Area of the tube x h x Specific weight  The surface tension force acting around the circumference of the tube = σ x πd.  The vertical component of this force = σ x πd x Cosθ —(i)
• 69. Equating the equations (i) and (ii)
• 70. Expression for Capillary fall  The glass tube is dipped in mercury, the level of mercury in tube will be lower than general level of outside liquid.
• 71. Bulk Modulus (K)  When a solid or fluid (liquid or gas) is subjected to a uniform pressure all over the surface, such that the shape remains the same, then there is a change in volume.  Then the ratio of normal stress to the volumetric strain within the elastic limits is called as Bulk modulus. This is denoted by K.
• 72.  where p = increase in pressure;  V = original volume;  ΔV = change in volume  The negative sign shows that with increase in pressure p, the volume decreases by Δ V i.e. if p is positive, Δ V is negative.
• 73. Compressibility.  The reciprocal of bulk modulus is called compressibility.
• 74. Vapour Pressure  Change of state from liquid to gaseous state is called vaporization.  This occurs due to continuous escape of molecules from free liquid surface.  Vaporization takes place at ……….temperature in atmospheric pressure.  When vaporization takes place, molecules escapes from free surface of the liquid and gets accumulated in space between liquid surface and top of vessel.  These vapours exerted pressure on liquid surface. This pressure is called vapour pressure of the liquid.
• 75. Why does food cook faster in a pressure cooker?
• 76. Trekking to KUMARA PARVATHA……!!!
• 77. Recall  Mass, weight, density, weight density, specific volume. (Formula and Units)  Viscosity- Dynamic and kinematic (Formula and Units) Reason for viscosity?? Effect of temperature??  Cohesion, adhesion- Examples  Surface tension- (Formula and Units) Example  Capillarity- Capillary rise and fall (Formula and Units) – Examples, day to day life example  Vapour pressure
• 78. Part-2 Fluid pressure and its measurements
• 79. Fluid Pressure  Fluid is a state of matter which exhibits the property of flow.  When a certain mass of fluids is held in static equilibrium by confining it within solid boundaries (Fig), it exerts force along direction perpendicular to the boundary in contact. This force is called fluid pressure (compression).
• 80. Pressure  Pressure is one of the basic properties of all fluids.  Pressure (p) is the force (F) exerted on or by the fluid on a unit of surface area (A).  Mathematically expressed:  The basic unit of pressure is Pascal (Pa). When a fluid exerts a force of 1 N over an area of 1m2, the pressure equals one Pascal, i.e., 1 Pa = 1 N/m2 1 bar =100kPa 1 Kpa=…….. N/m2
• 81. Pressure at a Point and Pascal’s Law  For a fluid at rest, the pressure at a given point is the same in all directions.  Pascal’s Law: States that “ pressure or intensity of pressure at a point in a static fluid is equal in all directions
• 86. Pressure variation in a fluid at rest
• 88. Absolute, gauge, atmospheric and vacuum pressures  The pressure on fluid is measured in two different systems.  In one system it is measured above complete vacuum pressure or absolute zero pressure  Other system is measured above atmospheric pressure
• 89. Absolute pressure:  It is defined as the pressure which is measured with reference to absolute vacuum pressure. Gauge Pressure:  It is defined as the pressure which is measured with the help of pressure measuring instrument, in which the atmospheric pressure is taken as datum. The atmospheric pressure is marked as zero.
• 91. Vacuum pressure:  It is defined as the pressure below the atmospheric pressure.  Mathematically,  Absolute pressure= Atmospheric pressure+ Gauge Pressure.  Vacuum pressure= Atmospheric pressure- Absolute pressure
• 92. Measurement of pressure  The pressure of a fluid is measure by the following devices.  Manometers  Mechanical Gauges  Electronic Gauges
• 93. MANOMETERS  Manometers are defined as the devices used for measuring the pressure at a point in a fluid by balancing the column of fluid by the same or another column of the fluid.  They are classified as  A) Simple manometers  B) Differential Manometers
• 94. SIMPLE MANOMETERS  A simple manometer consists of a glass tube having one of its ends connected to a point where pressure is to be measured and other end remains open to atmosphere.  Types of Simple Manometers are  Piezometer  U-tube Manometer  Single column Manometer
• 95. Piezometer  It is the simplest form of manometer used for measuring gauge pressures.  One end of this manometer is connected to the point where the pressure is to be measured and the other end is open to atmosphere.  The rise of liquid gives the pressure head at that point.
• 96. Piezometer