????????? (basic hydrodynamics)

1
????????? (basic hydrodynamics)

• 2-1 ???????????
• 2-2 ???????????
• 2-3 ????????
• 2-4 ?????????
• 2-5 ???????????
• 2-6 ????????????????
• 2-7 ?????????
• 2-8 ???????????,???????
• 2-9 ??????
• 2-10 ???????????
• 2-11 ???????????

2
2-1???????????(two methods to descriptions of
motion of liquid )

• ???????(Lagrangian method)(????method of
  material particles)
• ?????(Eulerian method)(????spatial description)

3
2-2 ?????????(the basic concepts of motion of
liquid)

• ? ???(steady flow)?????(unsteady flow)
• ? ???(one-dimensional flow)????(two-dimensional
  flow)????(three-dimensional flow)
• ???????????????
• ? ??(streamline)???(trace)
• ???????????????????
• ????????????,?????,??????????????????????????????
  ???
• ???????????????????,??????????
• ???????,???(nodal
  point)???(stagnation point)???
• 2????(streamlinear equation)

4

• ? ???????????????????????
• 1???(pipe flow)?????????????????????,?????,??????
  ???????,???????????????
• 2???(filament)?????????
• 3???(total flow)????????????
• 4?????(flow cross section)???????????????
• 5???(volume flow)???????????????? ?
• 6???????(average velocity of flow cross section)

5

• ????(uniform flow)?????(non-uniform flow)
• ???
• ???????????????????
• ???1??????2???????3??????????????,???????
• ???? ??????????????
• ? ???(gradually varied flow)????(rapidly varied
  flow)
• ??????????????????
• ???
• ?????????????????
• ???1????????? 2?????????,??????????3???????
  ?????????

6
2-3 ????????(the continuity of equation of
liquid)

• ????????????
• (differential equation of continuity of liquid)
• ??????????????(differential equation of
  continuity of incompressible fluid)

7

• ?????????????(continuity equation of filament and
  total flow)(??????law of energy conservation)
• ?????????(continuity equation of steady total
  flow)

8
2-4 ???????????(energy equation of ideal
liquid)

• ?????????????
• (differential equation of motion for real liquid)

9

• ??????????????????
• (Bernoulis integration and Bernoulis equation
  of real liquid)
• A ????
• 1 ???
• 2 ???????????
• 3 ?????
• 4 ?????
• B ??
• ????????

10

• ????????????????
• (piezometric head)
• z????(elevation head)
• ????(pressure head)
• ?????(principle of pitot tube)

11
2-5 ???????????(energy equation of total flow
for real liquid )

• ??????????????
• (Bernoulis equation of real liquid for
  filament)
• ?? ???????(loss of mechanical energy )
• ??????????????? (energy
  equation of steady total flow for real flow)

12

• ??????(energy equation)????????
• (1)????????????(head line)
• L-????
• ????(energy slope)
• ????????
• (slope of the hydraulic grade line)

13

• (2)????????????
• a)????(theorem of kinetic energy)????
• b)????????????? (law of
  conversation and transformation of energy)
• i)????
• ii)?????????
• iii)????????

14

• ??????????????????
• ????
• 1????
• 2????????,?????????
• 3???????????
• 4???????
• ????
• 1???????
• 2? ?????????????,??????? ????,?????????
• 3???????????

15

• 4???????
• 5???????????????,?????????
• ???????????????
• ????(water pump)????? ???

16
2-6 ????????????????(relation between energy
slope of steady uniform flow and shear stress)

• ????????????
• ? ?????????????(shear stress)???

17
2-7 ?????????(momentum equation of steady
total flow)

• ? ?????
• ????????
• ????

?
18

• ?????????
• 1?????????
• 2?????????????
• ????????
• 1?????????(free body)
• 2????????????????????(hydrodynamic pressure
  force)?????????????
• 3???????????
• 4????????????,?????
• ??????????

19
2-8???????????,???????

• ????????????? (basic movemental form of liquid
  element)
• 
  (1)??(translation)
• 
  (2)???(linear deformation)
• 
  (3)???(angular deformation)
• 
  (4)??(rotation)

20

• ?????
• (rate of linear
  deformation)
• 
  
• 
  ?????
• (rate of
  angular deformation)
• ?ABCD??????,
• ???????, ?????(angular velocity)
• ??????????

21

• ?????(rotational flow)????(irrotational flow)
• ????, ???????????
• ?
  (1)
• ????????????
• 
  (2)
• ?? ??????
• ?1,2?? ???(potential
  flow) ???

22
2-9 ??????(steady plane potential flow)

• ????????????(velocity potential)????
• 1??????(Laplace equation)
• 2???(stream function)
• ?????? 1) ? C??????
• 2) C??????
• 3)
• 4)???????,

23

• 3 ? ?????????(Cauchy-Riemann
  condition)
• ??????????(flow net)
• 1)???(equipotential line)? ????????
• 2)??? ????????
• 3)?????
• 1?????????
• 2?????????????

24
2-10???????????(differential equations of
motion for real liquid)

• ???????????
• ????
• (stress tensor )
• ??????????
• (reciprocal theorem of shear stress)
• ????,???????(Newtons law of viscosity)??

25

• ????????????
• ?????????????(differential equation of motion of
  real liquid)Navier-Stoke??

26

• ??????????????????? (Bernoulis
  integration of differential equation of motion
  for real flow) ????????
• ?????????????,
• ????,????,
• ?????????

27
2-11???????????(description of the problems of
cavity and cavitation)

• ??(cavity)???????????,??????????????
• ??(cavitation)?????????????????
• ???(cavitation number)
• ?? ????????????????????? ??????
  ????
• ?????(critical cavitation number) ,
  ?????