Fluid Mechanics for Chemical Quiz 8

1 / 50

Pick out the wrong statement ?

Turbulent fluid flow is characterised by the rapid fluctuation of instantaneous pressure & velocity at a point

In case of unsteady fluid flow, the velocity at any given point does not change with time

A hydrometer used for the determination of specific gravities of liquids works on the principle of buoyant forces

Surface tension of a liquid is because of the difference in magnitude of adhesive & cohesive forces

2 / 50

One dimensional fluid flow implies the __________?

Flow in straight lines only

Flow in which transverse components are zero

Steady uniform flow

Uniform flow

3 / 50

Piezometric head is the sum of the _______ heads?

Elevation & pressure

Elevation & kinetic energy

None of these

Kinetic energy & pressure

4 / 50

Prandtl number is a measure of the___________?

Cp/Cv of a fluid

Inertial force to elastic force in the fluid flow

Heat conduction to viscosity of a fluid

Elastic force to pressure force in the fluid flow

5 / 50

Pick out the correct statement pertaining to the flow through a converging-diverging tube ?

None of these

Throughout the converging portion of the tube, the density increases in the downstream direction

The value of Mach number is always unity at the throat

No shock wave develops in the tube when the Mach number at exit is greater than unity

6 / 50

Pick out the wrong statement?

Greater is the kinematic viscosity of the liquid, greater is the thickness of the boundary layer

Blowers develop a maximum pressure of 2 atmospheres

Fanning friction factor in case of turbulent flow of liquids in pipe depends upon relative roughness & Reynolds number

Friction losses in pipe fittings are generally expressed in terms of velocity heads

7 / 50

Non-colloidal solution is an example of the ________ fluid?

Non-Newtonian

Newtonian

Pseudo-plastic

Dilatent

8 / 50

Permanent loss in a Venturimeter is about ___________ percent of the pressure drop in the upstream cone?

9 / 50

Pick out the wrong statement about a streamline ?

It is a line across which there is no flow and it is equivalent to a rigid boundary

The fluid lying between any two streamlines can be considered to be in isolation and the streamline spacing varies inversely as the velocity

It is always parallel to the main direction of the fluid flow

Streamlines intersect at isolated point of zero velocity and infinite velocity

10 / 50

Out of the following flow measuring devices, which one incurs the maximum installation cost as well as pressure loss ?

Venturimeter

Orificemeter

Flow nozzle

Rotameter

11 / 50

Potential flow is characterised by the_____?

One in which dissipation of mechanical energy into heat occurs

Formation of eddies within the stream

Irrotational and frictional flow

Irrotational and frictionless flow

12 / 50

Pick out the wrong statement?

In the equation, T. gc = k. (du/dy)n the value of ?n? for pseudoplastic and Dilatant fluid are 1 respectively

Shear stress for Newtonian fluid is proportional to the rate of shear in the direction perpendicular to motion

The shear stress at the pipe (dia = D, length = L) wall in case of laminar flow of Newtonian fluids is (D/4L). ?p

With increase in the Mach number >0.6, the drag co-efficient decreases in case of compressible fluids

13 / 50

Pick out the wrong statement?

Existence of the boundary layer in fluid flow is because of viscosity of the fluid.

An ideal fluid is the one, which has negligible surface tension and obeys the Newton?s law of viscosity

The shear stress at any given cross-section of a pipe for steady flow (either laminar or turbulent) varies linearly as the radial distance

The form drag is dependent upon the occurrence of a wake

14 / 50

Open channel liquid flow is most conveniently measured by a___________?

Rotameter

Segmental orifice

Hot wire anemometer

Notch

15 / 50

Pick out the wrong statement ?

The viscosity of a non-Newtonian fluid is a function of temperature only

Momentum transfer in laminar flow results from velocity gradient

Both B. and C.

A fluid in equilibrium is not free from shear stress

16 / 50

Pitot tube measures the _______ of a fluid?

Average velocity

Point velocity

Pressure

Average flow rate

17 / 50

Pick out the wrong statement?

The vacuum pressure is always the negative gauge pressure

The pressure of the liquid measured by a piezometer tube is the gauge pressure

The point at which the resultant pressure on an immersed surface acts, is known as the centre of gravity

Manometric liquid should have high surface tension

18 / 50

Pressure co-efficient is the ratio of pressure forces to _____ forces?

Viscous

Gravity

None of these

Inertial

19 / 50

Pick out the wrong statement?

Laminar flow of viscous liquids is involved in the lubrication of various types of bearings

Newton?s law of viscosity is not applicable to the turbulent flow of fluid with linear velocity distribution

Rise of water in capillary tubes reduces with the increasing diameter of capillary tubes

A fluid mass is free from shearing forces, when it is made to rotate with a uniform velocity

20 / 50

Potential flow is the flow of_______?

Incompressible fluids with shear

Compressible fluids with shear

Incompressible fluids with no shear

Compressible fluids with no shear

21 / 50

Power loss in an orificemeter is ______ that in a Venturimeter?

Data insufficient, cannot be predicted

More than

Same as

Less than

22 / 50

One poise (unit of absolute/dynamic viscosity) is equivalent to one_______?

gm/cm. sec

m2/sec

cm2/sec

gm/cm2. sec

23 / 50

One dimensional flow implies__________?

A flow which does not account for changes in transverse direction

Steady uniform flow

Unsteady uniform flow

Flow in a straight line

24 / 50

Nominal size of the discharge pipe of a pump is usually ______ the nominal size of the inlet pipe?

Smaller than

Larger than

Twice

Same as

25 / 50

Power required by a centrifugal pump is proportional to (where, D = diameter, N = r.p.m) _________?

N3D5

N2D

ND2

N2D3

26 / 50

Pick out the wrong statement?

The eddy viscosity is a function of the type of turbulence involved

The eddy viscosity is a fluid property

The viscosity of a liquid increases with decrease in temperature

The viscosity of gas increases with increase in temperature

27 / 50

Paper pulp is an example of ______ fluid?

Pseudo-plastic

Bingham plastic

Dilatant

Newtonian

28 / 50

One horsepower is equal to_________?

Both A. and B.

550 kgf.m/second

550 lbf.ft./hr

550 lbf.ft/second

29 / 50

Potential function is applicable only for __________ flow?

Turbulent

None of these

Irrotational

Steady

30 / 50

Plunger pumps are used for___________?

Slurries

Higher pressure

Viscous mass

None of these

31 / 50

Pick out the correct statement?

In turbulent flow, there are neither cross-currents nor eddies

A forced vortex occurs when fluid rotates as a solid about an axis

In laminar flow, Newton?s law of viscosity does not apply

A free vortex occurs, when fluid rotates as a solid

32 / 50

Pick out the wrong statement ?

In a static mass of liquid, the pressure at a point is the same for all liquids

Atmospheric pressure = absolute pressure ? gage pressure

As per Pascal?s law, the pressure at a point in a static or uniformly moving fluid is equal in all directions

Pressure decreases exponentially with elevation in an isothermal atmosphere

33 / 50

Pascal?s law is valid, only when the fluid is_______?

Frictionless and at rest

At rest and when the frictionless fluid is in motion

None of these

At rest

34 / 50

Normal depth in open channel flow is the depth of flow in the channel ______?

Corresponding to uniform flow

None of these

Measured normal to the channel bed

Corresponding to steady flow

35 / 50

Pressure difference between two points in vessels, pipelines or in two different pipelines can be measured by a differential manometer. The pressure difference measured as the mm of water column in case of mercury-water, differential manometer is equal to (where, H = difference in height of mercury column in mm)?

14.6 H

13.6 H

12.6 H

36 / 50

Power number is the ratio of______?

Inertial stress to gravitational stress

Drag stress to inertial stress

Gravitational stress to drag stress

Inertial stress to drag stress

37 / 50

Power requirement of fans having constant wheel diameter varies ______ fan speed?

Directly as

As cube of

As square of

None of these

38 / 50

Prandtl mixing length is_____?

A universal constant

Zero at the pipe wall

None of these

Applicable to laminar flow problems

39 / 50

Path followed by water jet issuing from the bottom of a water tank will be a___________?

Parabola (vertex being at the opening)

Hyperbola

Horizontal straight line

Zig-zag path (which is geometrically undefined)

40 / 50

Pick out the correct statement?

Fanning friction factor is inversely proportional to Reynolds number always

Mach number in an incompressible fluid is always unity

The property of a randomly packed bed (with raschig rings) is given by the ratio of the total volume to the volume of voids in the bed

Mach number is given by the ratio of the speed of the fluid to that of sound in the fluid under conditions of flow

41 / 50

Pick out the correct statement pertaining to transition/ entrance length in fluid flow ?

Transition length for laminar flow of Newtonian fluids in a pipe of diameter ?d? is equal to 0.05. D.NRe

The length of entrance region of pipe, in which full development of fluid flow takes place such that velocity profile does not change downstream, is called the transition length

All A., B. and C.

Transition length for turbulent flow of Newtonian fluids in a smooth pipe of diameter ?d? is equal to 50 D

42 / 50

Nominal size of a pipe is an indication of its _______ diameter?

None of these

Outer

Approximate

Inner

43 / 50

Pascal law is not applicable for a/an __________ fluid?

Static

Accelerating frictionless

Uniformly moving

None of these

44 / 50

Pick out the correct statement?

A Newtonian fluid obeys Newton?s law of cooling

Human blood is a Newtonian fluid

For a non-Newtonian fluid, a straight line passes through the origin in a plot between shear stress and shear gradient

Thin lubricating oil is an example of a non-Newtonian fluid

45 / 50

Pipes having diameter 14 inches or more are designated by their__________?

None of these

Outside diameter

Inside diameter

Schedule number

46 / 50

Pick out the correct statement pertaining to Venturimeter ?

None of these

A Venturimeter with a fixed pressure drop discharges more, when the flow is vertically downward, than when the flow is vertically upward

The co-efficient of contraction of a Venturimeter is always unity

For a fixed pressure drop, the discharge of a gas through a Venturimeter is greater, when compressibility is taken into account, than when it is neglected

47 / 50

Pick out the wrong statement about cavitation?

Cavitation begins at higher static pressure and lower velocity in larger diameter pipelines resulting in audible noise

Cavitation may be caused due to boiling of liquid by decreasing the pressure resulting in formation & collapse of vapor cavities

Sudden reduction of pressure in a fluid flow system caused by flow separation, vortex formation or abrupt closing of valve leads to cavitation

Large scale cavitation cannot damage pipeline, restrict fluid flow and damage steam turbine blades

48 / 50

Power required for mixing Newtonian fluids is a function of the __________?

Density of fluid, viscosity of fluid & impeller dia only

Speed of impeller, diameter of impeller & viscosity

None of these

Density & viscosity of fluid only

49 / 50

Pick out the wrong statement pertaining to fluid flow ?

The ratio of average velocity to the maximum velocity for turbulent flow of Newtonian fluid in circular pipes is 0.5

Hagen-Poiseuille equation is applicable to the laminar flow of Newtonian fluids

The Newtonian fluid velocity in a circular pipe flow is maximum at the centre of the pipe

Navier-Stokes equation is applicable to the analysis of viscous flows

50 / 50

Permanent pressure loss in a well designed Venturimeter is about ______ percent of the venturi differential?

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