Chapter 1: Introduction Note to Students (the points emphasized in syllabus): The classroom time should be used to amplify the text book material by discussing related materials and applying basic principles to the solution of problems. The textbook should be a clear, concise presentation of the fundamentals that the student can read. Your willingness to read the text before going to class One learns best by doing --- you must solve problems! Follow formal solution procedure of the text.

© Fox, McDonald & Pritchard Main Topics Definition of a Fluid Scope of Fluid Mechanics Basic Laws Methods of Analysis Dimensions and Units

Definition of a Fluid

Scope of Fluid Mechanics To present basic laws and associated physical concepts that provide the basis or starting point in analysis of any problem in fluid mechanics Applications: Aircraft, surface ships/submarines, and automobiles (engines) Fluid machinery including pumps, fans, blowers, compressors, and turbines Thermal/chemical processes: boilers, heat exchangers, refinery, … Bio-fluids, blood flow Civil engineering, HVAC, flow in a pipe Anything that involves a fluid, such as a hurricane or tornado, …

Images of Some Typical Flows (Google)

Basic Laws The conservation of mass Newton’s second law of motion The principle of angular momentum The first law of thermodynamics The second law of thermodynamics The equation of state, such as pv =  RT The basic laws are the same as those used in mechanics (mechanics of materials) and thermodynamics. Our task will be to formulate these laws in suitable forms to solve fluid problems The last frontier of mechanics – more complex than any other mechanics

System Methods of Analysis System: A system is defined as a fixed quantity of mass – Closed system/Controlled mass The system boundaries separate the system from surroundings. The boundaries of the system may be fixed or movable; however, no mass crosses the system boundaries. (In mechanics courses – free-body diagram – system approach – the number of bodies is limited – in fluid, however, millions of particles – difficult to use the system approach)

Control volume A control volume is a (or an arbitrary) volume in space through which fluid flows. The geometric boundary of the control volume is called the control surface – may be real or imaginary – may be at rest or in motion

© Fox, McDonald & Pritchard Dimensions and Units Systems of Dimensions [M], [L], [t], and [T] [F], [L], [t], and [T] [F],[M], [L], [t], and [T]

© Fox, McDonald & Pritchard Dimensions and Units Systems of Units MLtT SI (kg, m, s, K) FLtT British Gravitational (lbf, ft, s, o R) FMLtT English Engineering (lbf, lbm, ft, s, o R)

© Fox, McDonald & Pritchard Dimensions and Units Preferred Systems of Units SI (kg, m, s, K) British Gravitational (lbf, ft, s, o R)

Dimensions and Units SI system: Unit of mass: kg; unit of length: m; unit of time: s, and the unit of temperature is the Kelvin K). Force (a secondary dimension) is the Newton (N). F = ma 1 N = 1 kg-m/s 2 The Absolute metric system: Unit of mass: gram ; unit of length: cm; unit of time: s, and the unit of temperature is the Kelvin K). Force (a secondary dimension) is the dyne 1 dyne = 1 g-cm/s 2 The British Gravitational system: Unit of force: the pound (lbf); unit of length: foot (ft); unit of time: s, and the unit of temperature is the degree Rankine ( o R). Mass (a secondary dimension) is the slug 1 slug = 1 lbf-s 2 /ft

Dimensions and Units The English Engineering system: The unit of force: lbf, the unit of mass: lbm, the unit of length: ft, unit of time: s, and the unit of temperature is the degree Rankine o R). Since both force and mass are chosen as primary dimensions, Newton’s second law is written as F = ma/g c A force of one pound (1 lbf) is the force that gives a pound mass (1lbm) an acceleration equal to the standard acceleration of gravity on Earh, 32.2 ft/s 2. From Newton’s second law g c = 32.2 ft-lbm/lbf-s 2 -- the constant of proportionality 1 slug = 32.2 lbm Preferred systems of units: Both the SI and the British Gravitational systems. In either case, g c = 1.