Fluid mechanics

Question 1

Density

Answer 1

Mass per unit of volume of a fluid

Question 2

Pressure

Answer 2

Force per unit area in a fluid

Question 3

Viscosity

Answer 3

Force per unit area due to the friction fluid arising from the relative motion of the neighboring elements in a fluid.

Question 4

Streamlines

Answer 4

The lines of the flow around an object in a fluid. Example: Wind tunnel

Question 5

Conservation of mass

Answer 5

The mass of fluid is equal at every point of a tube

Question 6

Mass continuity

Answer 6

conservation of mass

Question 7

Equation for conservation of mass

Answer 7

ρUA = constant

Question 8

Flow along a stream tube equation

Answer 8

ρ₁U₁A₁ = ρ₂U₂A₂

Question 9

Energy conservation in an ideal fluid

Answer 9

Bernoulli’s equation

Question 10

Bernoulli’s equation

Answer 10

Question 11

Hydrostatic pressure

Answer 11

The fluid at a given depth z is all at the same pressure p.

(In case the fluid is stationary: u=0)

Question 12

The significance of Bernoulli’s equation shows:

Answer 12

the pressure in a moving fluid decreases as the speed increases.

Question 13

coeficient of dynamic viscosicty (greek symbol):

Answer 13

μ

Question 14

The viscous shear force per unit of area (equation)

Answer 14

Question 15

Two different kinds of flow in a viscous fluid

Answer 15

• Laminar flow
• Turbulent flow

Question 16

Laminar flow

Answer 16

the fluid flows along distinct flow tubes and is stable

Question 17

Turbulent flow

Answer 17

The motion of the flow is disorderly and unstable

Question 18

Wheter a flow is laminar or turbulent is determined by

Answer 18

the Rennolds number

Question 19

Reynolds number equation

Answer 19

Question 20

Drag force

Answer 20

a net force in the direction of motion

Question 21

Drag force equation

Answer 21

D = 1/2C_dρU²A

Question 22

Lift force

Answer 22

D = 1/2C_lρU²A

Question 23

Drag coefficient

Answer 23

C_d

Question 24

Lift coefficient

Answer 24

C_l

Question 25

A fluid can be a

Answer 25

* Liquid * Gas

Question 26

Important properties of a fluid

Answer 26

* Density * Pressure * Viscosity

Question 27

Paramaters of a flowing fluid

Answer 27

* Speed * Volume flow * Mass flow

Question 28

2 types of hydro turbines

Answer 28

1. uses potential energy to convert to conetic energy 2. uses pressure to power turbine

Question 29

Drag and lift force are

Answer 29

air resistance, fluid resistance in the direction of the flow