武汉大学：《水力学 hydraulics》课程教学资源（PPT课件）Chapter I Introduction、Chapter II Hydrostatics

Chapter I WHU Introduction 1.1 Some characteristics of fluids 1.2 Dimensions and units 1.4 Fluid Mass and Weight 1.6 Viscosity 1.7 Compressibility of Fluid 1.9 Surface tension 1.10 Forces acting on fluid

WHU Chapter I Introduction 1.1 Some Characteristics of Fluids 1.2 Dimensions and Units 1.4 Fluid Mass and Weight 1.6 Viscosity 1.7 Compressibility of Fluid 1.9 Surface Tension 1.10 Forces acting on fluid

1.1 Some Characteristics of WHU Matter has 3 states: Solid: definite volume, definite shape Liquid: definite volume, no-definite shape Gas: no-definite volume, no-definite shape Fluid: deforms continuously when acted on by shearing stresses of any magnitude

WHU 1.1 Some Characteristics of Fluids Matter has 3 states: Solid: definite volume, definite shape Liquid: definite volume, no-definite shape Gas: no-definite volume, no-definite shape Fluid: deforms continuously when acted on by shearing stresses of any magnitude

Continuum Hypothesis WHU It is considered that fluid is such a continuous medium which consists of many particles. There are no interval between the fluid particles which fill the space occupied by fluid

WHU Continuum Hypothesis It is considered that fluid is such a continuous medium which consists of many particles. There are no interval between the fluid particles which fill the space occupied by fluid

Study object of Hydraulics WHU Study mechanical movement of liquid which give priority to water. Liquid: ODefine volume: imcompressible ONo-define shape: deform or fluidity

WHU Study Object of Hydraulics Study mechanical movement of liquid which give priority to water. Liquid: ●Define volume: imcompressible; ●No-define shape: deform or fluidity

L2 Dimensions and units WHU The system of international units(SD) is used in Hydraulics Dimensions of sl: LL: length; IT: time; M: mass [x]=[LPMRi

WHU 1.2 Dimensions and Units The system of international units (SI) is used in Hydraulics. • Dimensions of SI: [L]: length; [T]: time; [M]: mass [ ] [ ]   M  x = L T

Classify of Parameters WHU 区无法显示该图片 D=LTpMr Geometrical parameters: a+0; B=r=0 Movement parameters:尸≠0;y=0 Dynamical parameters 7≠O Non-dimension Parameters a=B=y=0

WHU Classify of Parameters Geometrical parameters: Movement parameters: Dynamical parameters: Non-dimension Parameters: [ ] [ ]   M  x = L T   0; =  = 0   0; = 0   0  =  =  = 0

WHU Units of si Length: m; cm; mm; km Time: s: h: d Mass: kg: g: mg: t Force:N:KN。 21'=2.54cm;1t=12=30.48cm 21Ib=45359g

WHU Units of SI Length: m; cm; mm; km… Time: s; h; d… Mass: kg; g; mg; t… Force: N; KN… *1'=2.54cm; 1ft=12'=30.48cm *1Ib=453.59g

WHU 1 4 Fluid Mass and Weight 1. Density p The density of fluid is mass per unit volume。 The density of fluid changes in temperature and pressure Unit ofp: kg/m3: g/m3: ke/cm3 o]=[N2]

WHU 1.4 Fluid Mass and Weight 1. Density The density of fluid is mass per unit volume. The density of fluid changes in temperature and pressure. Unit of : kg/m3 ; g/m3 ; kg/cm3 …  [ ] [ ] −3  = ML 

Density of Water WHU Density of liquids varies small in 84p=100g pressure and temperature The density of water can be as constant 60 P=1000/g/m3 tmperature℃ I FIGURE 1.1 Density of water as a function of temperature

WHU Density of Water Density of liquids varies small in pressure and temperature. The density of water can be as constant. 3  =1000k g / m

WHU 2. Specific Weight r The specific weight of fluid is weight per unit volume, it changes in pressure and temperature. Unit of y: N/m3: KN/m3 Ly=Ml T -pg

WHU 2. Specific Weight The specific weight of fluid is weight per unit volume, it changes in pressure and temperature. Unit of : N/m3 ; KN/m3   =  g  [ ] [ ] −2 −2  = ML T