Fluid Dynamics

Question 1

Uniform flow

Answer 1

the velocity has the same magnitude and direction at every point

Question 2

Non-uniform flow

Answer 2

At a given instant, the velocity is not the same everywhere

Question 3

Steady flow

Answer 3

Velocity, pressure and cross section may differ from point to point but do not change with time

Question 4

Unsteady flow

Answer 4

Velocity, pressure and cross section may differ with time

Question 5

One dimensional flow

Answer 5

Parameters at given instant in time only vary in the direction of flow

Question 6

Two dimensional flow

Answer 6

Flow parameters vary in the direction of flow and in one direction at right angles to this direction.

Question 7

Three dimensional flow

Answer 7

Flow parameters vary in direction of flow and in the two directions at right angles to this direction.

Question 8

Streamlines

Answer 8

Path of imaginary particles in a fluid

Question 9

3 facts about streamlines

Answer 9

Close to a solid boundary, streamlines are parallel to that boundary

Streamlines can not cross each other

Any particle starting in one streamlines will stay in the same streamline

Question 10

Streamtube

Answer 10

Collection of streamlines

Question 11

Key difference between streamlines and streamtubes

Answer 11

Streamlines are two dimensional while streamtubes are three dimensional

Question 12

Volume flow rate

Answer 12

Volume of fluid flowing per unit time

Question 13

Mass flow rate

Answer 13

Mass of fluid flowing per unit time

Question 14

Mean velocity flow

Answer 14

Discharge (Q) divided by cross section area (A)

Question 15

Inviscid flow

Answer 15

Flow of fluid with no viscosity

Question 16

Continuity equation

Answer 16

Conservation of mass

Question 17

Bernoulli’s equation

Answer 17

Conservation of energy

Question 18

Momentum equation

Answer 18

Conservation of momentum

Question 19

Energies

Answer 19

0.5mV²=>0.5(ρAV)xV²
mgh=>(ρAV)gh
(pA)xV

Question 20

Total energy power unit weight

Answer 20

V²/2g+h+p/ρg=constant

Question 21

Bernoulli’s equation

Answer 21

V²/2g+h+p/ρg before = V²/2g+h+p/ρg after

Question 22

Volume of flow through small orifice

Answer 22

V₂=√(2gh)

Question 23

Conservation of momentum so

Answer 23

F=d(mV)/dt

Force equals momentum change rate

Question 24

All the forces equation

Answer 24

FT=FR+FP+FB

Question 25

As an application of the momentum equation, what does the control column include?

Answer 25

Faces at inlet and outlet of bend and pipe walls

Question 26

As an application of the momentum equation, why is the coordinates system

Answer 26

An axis is pointing in the direction of the inlet velocity

Question 27

Total force equation

Answer 27

F=ρ(Q₂V₂-Q₁V₁)

Question 28

Force on a pelton wheel blade

Answer 28

FTX=ρQ(V₂cosβ+V₁)