Fluid Analysis and Application

Question 1

what is fluid

Answer 1

In Physics, fluid is a substance that continually deform under an applied shear stress, no matter how small it is.

Question 2

what is density

Answer 2

ratio of the mass of a fluid to its volume

Question 3

what is specific volume

Answer 3

volume occupied by unit mass. it is reciprocal of density.

Question 4

what is relative density

Answer 4

the ratio of its density to the density of a given reference material

Question 5

what is specific gravity

Answer 5

the ratio of its weight to the weight of an equal volume of water at standard condition

Question 6

what is compressibility

Answer 6

measure of relative volume change of a fluid, as the response of pressure. the decrease of volume per unit volume of fluid is called coefficient of compressibility

Question 7

what is bulk modulus of elasticity

Answer 7

the reciprocal of coefficient of volume compressibility

Question 8

specific weight

Answer 8

weight per unit volume

Question 9

what is viscosity

Answer 9

resistance of fluid depends upon its cohesion and rate of transfer molecular momentum

Question 10

predominant cause of viscosity

Answer 10

1) cohesion (cause of viscosity of liquid)
2) transfer molecular momentum (cause of viscosity of gas)

Question 11

dynamic viscosity

Answer 11

absolute viscosity

Question 12

kinematic viscosity

Answer 12

ratio of dynamic viscosity to density

Question 13

what are the motion parameters

Answer 13

velocity, acceleration, density, pressure, temperature, viscosity force

Question 14

path line

Answer 14

trajectory of an individual fluid particle in a flow field during a period of time

Question 15

stream line

Answer 15

continous line (many different fluid particles) drawn within the fluid field at a certain instant.

Question 16

flow section

Answer 16

section that every area element in the section is normal mini-steam tube or stream line

Question 17

flow rate

Answer 17

the amount of fluid passing through the cross section in unit interval

Question 18

average velocity

Answer 18

according to the equivalency of flow rate is called the section average velocity

Question 19

control volume

Answer 19

invariable hollow volume in space/moving with constant velocity through which the fluid flows

Question 20

steady flow

Answer 20

motion parameters independent of time

Question 21

unsteady flow

Answer 21

motion parameters dependent on time

Question 22

differential manometer

Answer 22

used to measure 2 container or 2 points in a container

Question 23

the discharge passing through a fixed cross section is

Answer 23

rectanglar and annular section

Question 24

frictional loss

Answer 24

pressure drop for laminar flow and turbulent flow in horizontal circular tube

Question 25

minor resistance

Answer 25

the losses just occur locally, which called minor energy losses or minor pressure losses

Question 26

reynold numbers (Re)

Answer 26

head losses comprises of friction losses and minor losses. used to describe the characteristic of flow

Question 27

newtonian

Answer 27

gamma is constant (gas & thin liquids)

Question 28

non newtonian

Answer 28

gamma is not constant (thick, long chained hydrocarbons)

Question 29

physical meaning of :-
- Z
- P/pg

Answer 29

Z - position potential energy per unit weight of fluid
P/pg - pressure potential energy per unit weight of fluid

Question 30

geometrical meaning of :-
- Z
-P/pg

Answer 30

Z - elevation head
P/pg - pressure head

Question 31

vacuum pressure

Answer 31

suction pressure, also known as negative pressure

Question 32

gravity

Answer 32

only mass force acting on a liquid

Question 33

system definition, characteristics and its method

Answer 33

definition - a collection of fluid matter of fixed identity that will move, flow and interact with its surroundings.

characteristics - can change shape, volume and boundary with time. can move and has the exchange of energy but no mass.

method - lagrangian method

Question 34

control volume definition, characteristics and its method

Answer 34

definition - invariably hollow volume in space or moving with constant velocity through which fluid flows.

characteristics - shape, volume and boundary cannot change. it is fixed. has mass exchanger and energy

method - eulerian method

Question 35

absolute pressure

Answer 35

the measurement of pressure in relation to zero. since a negative value would sugget tension, all absolute pressure values are positive.

Question 36

gauge pressure

Answer 36

when we measure it using atmospheric pressure as a base. the value would be positive if it is higher atmopsheric pressure and negative if it is vacuum condition.

Question 37

vacuum

Answer 37

when the pressure is lower than the atmospheric pressure and gauge is the margin by which is lower.

Question 38

real fluid

Answer 38

have velocity, and when they are in motion, the 2 layers contacting will experiemce tangential as well as normal stress

Question 39

ideal fluid and example

Answer 39

have no velocity, and when in motion, the 2 layers will not experience tangential stress but act on each other with normal force.

ideal fluid is also known as frictionless fluid and no such fluid exist in nature. the example of ideal fluid cannot be provided as it does not exist in the real world but only in theory