Note for Fluid Mechanics - FM By JNTU Heroes

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Fluid Mechanics Fluid Mechanics 2nd Year Civil Engineering 1

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Fluid Mechanics Contents 1. Introduction ......................................................................................................... 7 1.1 Course Outline ............................................................................................... 7 Goals .............................................................................................................. 7 Syllabus.......................................................................................................... 8 1.2 Programme ..................................................................................................... 9 Lectures.......................................................................................................... 9 Assessment..................................................................................................... 9 1.3 Reading Material.......................................................................................... 10 Lecture Notes ............................................................................................... 10 Books ........................................................................................................... 10 The Web....................................................................................................... 10 1.4 Fluid Mechanics in Civil/Structural Engineering ........................................ 11 2. Introduction to Fluids ....................................................................................... 12 2.1 Background and Definition.......................................................................... 12 Background .................................................................................................. 12 Definition ..................................................................................................... 13 Definition Applied to Static Fluids.............................................................. 13 Definition Applied to Fluids in Motion ....................................................... 14 Generalized Laws of Viscosity .................................................................... 17 2.2 Units ............................................................................................................. 19 Dimensions and Base Units ......................................................................... 19 Derived Units ............................................................................................... 19 SI Prefixes .................................................................................................... 21 Further Reading ........................................................................................... 21 2.3 Properties ..................................................................................................... 22 Further Reading ........................................................................................... 22 Mass Density................................................................................................ 22 2

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Fluid Mechanics Specific Weight............................................................................................ 22 Relative Density (Specific Gravity)............................................................. 22 Bulk Modulus............................................................................................... 23 Viscosity....................................................................................................... 23 Problems - Properties................................................................................... 25 3. Hydrostatics ....................................................................................................... 26 3.1 Introduction.................................................................................................. 26 Pressure ........................................................................................................ 26 Pressure Reference Levels ........................................................................... 27 3.2 Pressure in a Fluid........................................................................................ 28 Statics of Definition ..................................................................................... 28 Pascal’s Law ................................................................................................ 29 Pressure Variation with Depth..................................................................... 31 Summary ...................................................................................................... 33 Problems - Pressure...................................................................................... 34 3.3 Pressure Measurement ................................................................................. 36 Pressure Head............................................................................................... 36 Manometers.................................................................................................. 36 Problems – Pressure Measurement .............................................................. 41 3.4 Fluid Action on Surfaces ............................................................................. 43 Plane Surfaces .............................................................................................. 43 Plane Surface Properties .............................................................................. 46 Plane Surfaces – Example............................................................................ 47 Curved Surfaces ........................................................................................... 51 Curved Surfaces – Example......................................................................... 55 Problems – Fluid Action on Surfaces .......................................................... 57 4. Hydrodynamics: Basics..................................................................................... 59 4.1 General Concepts ......................................................................................... 59 Introduction.................................................................................................. 59 3

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Fluid Mechanics Classification of Flow Pattern...................................................................... 59 Visualization ................................................................................................ 60 Dimension of Flow ...................................................................................... 62 Fundamental Equations................................................................................ 63 Control Volume ........................................................................................... 64 4.2 The Continuity Equation.............................................................................. 65 Development ................................................................................................ 65 Mass Conservation – Example .................................................................... 68 4.3 The Energy Equation ................................................................................... 71 Development ................................................................................................ 71 Comments .................................................................................................... 74 Energy Equation – Example ........................................................................ 75 4.4 The Momentum Equation ............................................................................ 78 Development ................................................................................................ 78 Application – Fluid Striking a Flat Surface................................................. 79 Application – Flow around a bend in a pipe................................................ 81 Application – Force exerted by a firehose................................................... 83 4.5 Modifications to the Basic Equations .......................................................... 86 Flow Measurement – Small Orifices ........................................................... 86 Flow Measurement – Large Orifices ........................................................... 89 Discharge Measurement in Pipelines........................................................... 92 Velocity and Momentum Factors ................................................................ 94 Accounting for Energy Losses..................................................................... 96 Problems – Energy Losses and Flow Measurement.................................... 99 5. Hydrodynamics: Flow in Pipes ...................................................................... 100 5.1 General Concepts ....................................................................................... 100 Characteristics of Flow Types ................................................................... 103 Background to Pipe Flow Theory.............................................................. 104 5.2 Laminar Flow............................................................................................. 105 4