Lec 1

Question 1

pressure arises from

Answer 1

collisions of molecules with the walls of the container and each other and gravitational force - weight of fluid

Question 2

pressure always acts

Answer 2

at right angles to any surface otherwise liquid would flow

Question 3

pressure head =

Answer 3

Force of whatever the substance is over 1 m^2

1mmH20 = Vdensityg/A=1/1000 *1000 *9.8 /1 = 9.8 Pa

Question 4

gauge pressure equation

Answer 4

absolute pressure = atmospheric pressure + gauge pressure

Question 5

pressure due to depth

Answer 5

pressure = pressure at the top + density * g * height (or depth)

Question 6

buoyancy equation

Answer 6

apparent weight = weight of object - weight of displaced water
if floating weight of object = weight of displaced water

Question 7

pascals principle and hydraulics

Answer 7

pressure is constant F1/A1 = F2/A2

Question 8

vapour pressure is pressure due to

Answer 8

molecules in gas state

Question 9

number of molecules escaping fluids surface =number of returning molecules

Answer 9

saturation or equilibrium

Question 10

when vapour pressure = atmospheric pressure

Answer 10

boiling

Question 11

low vapour pressure

Answer 11

liquid will evaporate into air quickly

Question 12

viscosity is

Answer 12

internal stickiness of a fluid (measures how quickly a liquid responds to shear stress, high viscosity responds a lower rate)

Question 13

liquid flows under action

Answer 13

of shear stress (response not instantaneous throughout liquid)

Question 14

shear stress =

Answer 14

• viscosity * velocity gradient

Question 15

kinematic viscosity =

Answer 15

viscosity / density

Question 16

how is a velocity gradient setup (diagram)

Answer 16

lower plate starts moving drags fluid next to it along

fluid next to top surface remains stationary

Question 17

factors that affect viscosity

Answer 17

pressure and temperature

Question 18

how does viscoisty change with temperature

Answer 18

exponentially viscosity = viscosity consant e^(constant *temperature)

Question 19

Newtonian fluids are

Answer 19

fluids with constant viscosity (shear stress against - viscosity gradient is straight line with viscosity as gradient)

Question 20

nonnewtonian fluid

Answer 20

fluids without constant viscosity

Question 21

bingham pastes

Answer 21

minimum shear stress to be exceeded for flow

Question 22

shear thinning fluids

Answer 22

become less viscous as shear stress is applied

Question 23

shear thickening fluids

Answer 23

become more viscous as shear stress is applied

Question 24

two types of fluid flow

Answer 24

laminar

turbulent

Question 25

different line types

Answer 25

pathline
streakline
streamline

Question 26

pathline

Answer 26

history of a particles location
pooh sticks
put particle in where it is at at any given time

Question 27

streakline

Answer 27

instantenous line whose points are occupied by all particles originating from some specified point in a flow field
pouring ink constantly into flow from specific point

Question 28

streamline

Answer 28

line in the flow where velocity vector of each particle occupying a point on the streamline is tangent to the streamline
fluid particle can never cross a streamline (streamtube formed by joining a bundle of neighbouring streamlines)

Question 29

1D flow

Answer 29

has x component only - horizontal

Question 30

2D flow

Answer 30

x and y component of velocity