Aula 1 Mecânica dos Fluidos Sandro R. Lautenschlager

Apresentação em tema: "Aula 1 Mecânica dos Fluidos Sandro R. Lautenschlager"— Transcrição da apresentação:

1 Aula 1 Mecânica dos Fluidos Sandro R. Lautenschlager
1-Considerações Básicas

2 Mecânica dos Fluidos Definição
Estudo dos líquidos e gases no qual não há movimento (estáticos) e naqueles no qual há movimentos (dinâmica)

3 History Faces of Fluid Mechanics Archimedes Newton Leibniz Bernoulli
(C BC) Newton ( ) Leibniz ( ) Bernoulli ( ) Euler ( ) Navier ( ) Stokes ( ) Reynolds ( ) Prandtl ( ) Taylor ( )

4 Weather & Climate Tornadoes Thunderstorm Global Climate Hurricanes

5 Vehicles Aircraft Surface ships High-speed rail Submarines

6 Environment Air pollution River hydraulics

7 Physiology and Medicine
Blood pump Ventricular assist device

8 Sports & Recreation Water sports Cycling Offshore racing Auto racing
Surfing

9 Aplicação em engenharia
Computer Simulations Save US $150,000 in Commuter Jet Design by Reducing Wind Tunnel Testing

10 Aplicação em engenharia

11 Aplicação em engenharia

12 Aplicação em engenharia

13 Propriedades dos Fluidos
Peso específico Onde: g-gravidade local (9,8 m/s2); r-massa especifica (kg/m3); g-peso específico (kg/m2s2) ou N/m3

14 Propriedades dos Fluidos
Densidade Temperatura de referência 40C

15 Variação de com a temperatura

16 Massa Específica

17

18 Peso Específico

19 Massa Especifica (kg/m3)
Nas condições Normais Massa Especifica (kg/m3) Peso Especifico (N/m3) Densidade Ar 1,23 12,1 0,00123 Água 1000 9810 1

20 Some Simple Flows Flow between a fixed and a moving plate
Fluid in contact with the plate has the same velocity as the plate u = x-direction component of velocity u=V Moving plate Fixed plate y x V u=0 B Fluid

21 Some Simple Flows Flow through a long, straight pipe
Fluid in contact with the pipe wall has the same velocity as the wall u = x-direction component of velocity r x R V Fluid

22 Fluid Deformation Flow between a fixed and a moving plate
Force causes plate to move with velocity V and the fluid deforms continuously. u=V Moving plate Fixed plate y x u=0 Fluid t0 t2 t1

23 Fluid Deformation Shear stress on the plate is proportional
to deformation rate of the fluid u=V+dV Moving plate Fixed plate y x u=V Fluid dx dy da dL t t+dt

24 Shear in Different Fluids
Shear-stress relations for different types of fluids Newtonian fluids: linear relationship Slope of line (coefficient of proportionality) is “viscosity”

25 Viscosity Newton’s Law of Viscosity Viscosity Units Water (@ 20oC)
m = 1x10-3 N-s/m2 Air 20oC) m = 1.8x10-5 N-s/m2 Kinematic viscosity V V+dv

26 Force acting ON the plate
Flow between 2 plates Force is same on top and bottom Thus, slope of velocity profile is constant and velocity profile is a st. line u=V Moving plate Fixed plate y x V u=0 B Fluid Force acting ON the plate

27 Flow between 2 plates Shear stress anywhere between plates y
Moving plate u=V V t Shear on fluid B t x Fixed plate u=0

28 Flow between 2 plates 2 different coordinate systems r x B V y x

29 Example: Journal Bearing
Given Rotation rate, w = 1500 rpm d = 6 cm l = 40 cm D = 6.02 cm SGoil = 0.88 noil = m2/s Find: Torque and Power required to turn the bearing at the indicated speed.

30 Example: cont. Assume: Linear velocity profile in oil film

31 Compressibilidade Módulo de elasticidade volumétrica

32 Módulo de elasticidade para água
B=2100MPa ou 21000x atm Mudança 1% Líquidos podem ser considerados incompressíveis 21Mpa (210atm)

33 Cálculo velocidade do som
Exemplo para água c = 1450m/s (condições normais )

34 Data da Provas P1 17/08/11 Cap. 1 e 2; P2 05/10/11 Cap. 3 e 4;
Exame 5/12/11 Avaliação final Cap. 1, 2, 3, 4 e 6