Fluid Mechanics for Chemical Quiz 8

1 / 50

Pick out the correct statement?

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

A free vortex occurs, when fluid rotates as a solid

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

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

2 / 50

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

3 / 50

Pick out the wrong statement?

The eddy viscosity is a fluid property

The viscosity of a liquid increases with decrease in temperature

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

The viscosity of gas increases with increase in temperature

4 / 50

Pick out the wrong statement?

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

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

The vacuum pressure is always the negative gauge pressure

5 / 50

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

m2/sec

gm/cm. sec

gm/cm2. sec

cm2/sec

6 / 50

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

Venturimeter

Flow nozzle

Rotameter

Orificemeter

7 / 50

Pick out the wrong statement ?

Atmospheric pressure = absolute pressure ? gage pressure

Pressure decreases exponentially with elevation in an isothermal atmosphere

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

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

8 / 50

Pick out the wrong statement?

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

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

The form drag is dependent upon the occurrence of a wake

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

9 / 50

Pick out the wrong statement?

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

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

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

10 / 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)

11 / 50

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

None of these

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

The value of Mach number is always unity at the throat

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

12 / 50

Potential flow is characterised by the_____?

Formation of eddies within the stream

Irrotational and frictionless flow

One in which dissipation of mechanical energy into heat occurs

Irrotational and frictional flow

13 / 50

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

None of these

At rest and when the frictionless fluid is in motion

Frictionless and at rest

At rest

14 / 50

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

None of these

Accelerating frictionless

Uniformly moving

Static

15 / 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

16 / 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

17 / 50

Power number is the ratio of______?

Inertial stress to gravitational stress

Inertial stress to drag stress

Gravitational stress to drag stress

Drag stress to inertial stress

18 / 50

Pick out the correct statement?

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

Fanning friction factor is inversely proportional to Reynolds number always

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 in an incompressible fluid is always unity

19 / 50

Pick out the wrong statement ?

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

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

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

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

20 / 50

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

Larger than

Twice

Smaller than

Same as

21 / 50

Pitot tube measures the _______ of a fluid?

Average flow rate

Pressure

Point velocity

Average velocity

22 / 50

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

Less than

Data insufficient, cannot be predicted

Same as

More than

23 / 50

Piezometric head is the sum of the _______ heads?

Elevation & kinetic energy

Kinetic energy & pressure

Elevation & pressure

None of these

24 / 50

Pick out the correct statement?

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

A Newtonian fluid obeys Newton?s law of cooling

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

25 / 50

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

Measured normal to the channel bed

None of these

Corresponding to steady flow

Corresponding to uniform flow

26 / 50

Prandtl number is a measure of the___________?

Heat conduction to viscosity of a fluid

Inertial force to elastic force in the fluid flow

Elastic force to pressure force in the fluid flow

Cp/Cv of a fluid

27 / 50

One horsepower is equal to_________?

550 lbf.ft./hr

550 kgf.m/second

550 lbf.ft/second

Both A. and B.

28 / 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

29 / 50

One dimensional flow implies__________?

A flow which does not account for changes in transverse direction

Flow in a straight line

Steady uniform flow

Unsteady uniform flow

30 / 50

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

Density & viscosity of fluid only

Speed of impeller, diameter of impeller & viscosity

None of these

Density of fluid, viscosity of fluid & impeller dia only

31 / 50

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

32 / 50

Potential function is applicable only for __________ flow?

Irrotational

Steady

None of these

Turbulent

33 / 50

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

Inner

None of these

Outer

Approximate

34 / 50

One dimensional fluid flow implies the __________?

Steady uniform flow

Flow in which transverse components are zero

Flow in straight lines only

Uniform flow

35 / 50

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

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

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

36 / 50

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

As cube of

None of these

As square of

Directly as

37 / 50

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

Outside diameter

None of these

Inside diameter

Schedule number

38 / 50

Plunger pumps are used for___________?

None of these

Slurries

Higher pressure

Viscous mass

39 / 50

Potential flow is the flow of_______?

Compressible fluids with shear

Compressible fluids with no shear

Incompressible fluids with no shear

Incompressible fluids with shear

40 / 50

Pick out the wrong statement ?

A fluid in equilibrium is not free from shear stress

Both B. and C.

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

Momentum transfer in laminar flow results from velocity gradient

41 / 50

Paper pulp is an example of ______ fluid?

Dilatant

Bingham plastic

Newtonian

Pseudo-plastic

42 / 50

Open channel liquid flow is most conveniently measured by a___________?

Hot wire anemometer

Notch

Rotameter

Segmental orifice

43 / 50

Pick out the wrong statement?

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

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

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

Blowers develop a maximum pressure of 2 atmospheres

44 / 50

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

Dilatent

Non-Newtonian

Newtonian

Pseudo-plastic

45 / 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

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

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

46 / 50

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

ND2

N2D

N2D3

N3D5

47 / 50

Pick out the correct statement pertaining to Venturimeter ?

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

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

48 / 50

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

Inertial

Viscous

None of these

Gravity

49 / 50

Prandtl mixing length is_____?

None of these

A universal constant

Zero at the pipe wall

Applicable to laminar flow problems

50 / 50

Pick out the wrong statement about a streamline ?

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

Streamlines intersect at isolated point of zero velocity and infinite velocity

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

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