99 + Interview Questions in Fluid Mechanics Page 1 InterviewSolution

1.	The head over a V-notch at the end of a channel is 75 cm. If an error of 0.15 cm is possible In the measurement of the head, then the percentage error in computing the discharge is
Answer» The head over a V-notch at the end of a channel is 75 cm. If an error of 0.15 cm is possible In the measurement of the head, then the percentage error in computing the discharge is

Discussion

2.	What is the momentum thickness for the boundary layer with velocity distribution uU=yδ?
Answer» What is the momentum thickness for the boundary layer with velocity distribution $\frac{u}{U} = \frac{y}{δ}$ ?

Discussion

3.	The velocity field of an incompressible flow is given byV= (a1x+a2y+a3z)i+(b1x+b2y+b3z)j+(c1x+c2y+c3z)k, where a1=2 and c3=−4. The value of b2 is______2
Answer» The velocity field of an incompressible flow is given by $V = (a_{1} x + a_{2} y + a_{3} z) i + (b_{1} x + b_{2} y + b_{3} z) j + (c_{1} x + c_{2} y + c_{3} z) k,$ where $a_{1} = 2$ and $c_{3} = - 4$ . The value of $b_{2}$ is______ 2

Discussion

4.	Two immiscible, incompressible, viscous fluids having same densities but different viscosities are contained between two infinite horizontal parallel plates, 2 m apart as shown below. The bottom plate is fixed and the upper plate moves to the right with a constant velocity of 3 m/s. With the assumptions of Newtonian fluid, steady and fully developed laminar flow with zero pressure gradient in all directions, the momentum equations simplify to d2udy2=0If the dynamic viscosity of the lower fluid μ2, is twice that of the upper fluid μ1, then the velocity at the interface (round off to two decimal places) is m/s.1
Answer» Two immiscible, incompressible, viscous fluids having same densities but different viscosities are contained between two infinite horizontal parallel plates, 2 m apart as shown below. The bottom plate is fixed and the upper plate moves to the right with a constant velocity of 3 m/s. With the assumptions of Newtonian fluid, steady and fully developed laminar flow with zero pressure gradient in all directions, the momentum equations simplify to $\frac{d^{2} u}{d y^{2}} = 0$ If the dynamic viscosity of the lower fluid $μ_{2}$ , is twice that of the upper fluid $μ_{1},$ then the velocity at the interface (round off to two decimal places) is m/s. 1

4.

Two immiscible, incompressible, viscous fluids having same densities but different viscosities are contained between two infinite horizontal parallel plates, 2 m apart as shown below. The bottom plate is fixed and the upper plate moves to the right with a constant velocity of 3 m/s. With the assumptions of Newtonian fluid, steady and fully developed laminar flow with zero pressure gradient in all directions, the momentum equations simplify to d2udy2=0If the dynamic viscosity of the lower fluid μ2, is twice that of the upper fluid μ1, then the velocity at the interface (round off to two decimal places) is m/s.1

Answer»

Two immiscible, incompressible, viscous fluids having same densities but different viscosities are contained between two infinite horizontal parallel plates, 2 m apart as shown below. The bottom plate is fixed and the upper plate moves to the right with a constant velocity of 3 m/s. With the assumptions of Newtonian fluid, steady and fully developed laminar flow with zero pressure gradient in all directions, the momentum equations simplify to

$\frac{d^{2} u}{d y^{2}} = 0$

If the dynamic viscosity of the lower fluid $μ_{2}$ , is twice that of the upper fluid $μ_{1},$ then the velocity at the interface (round off to two decimal places) is m/s.

1

Discussion

5.	For a two-dimensional irrotational flow, the velocity potential is defined as ϕ=loge (x2+y2). Which of the following is a possible stream function, ψ, for this flow?
Answer» For a two-dimensional irrotational flow, the velocity potential is defined as $ϕ = l o g_{e} (x^{2} + y^{2})$ . Which of the following is a possible stream function, $ψ$ , for this flow?

Discussion

6.	For accurate flow measurement in open channels, an arrangement for aeration under the nappe is necessary when the weir used is
Answer» For accurate flow measurement in open channels, an arrangement for aeration under the nappe is necessary when the weir used is

Discussion

7.	A triangular gate with a base width of 2 m and a height of 1.5 m lies in a vertical plane. The top vertex of the gate is 1.5 m below the surface of a tank which contains oil of specific gravity 0.8. Considering the density of water and acceleration due to gravity to be 1000 kg/m3 and 9.81 m/s2 respectively, the hydrostatic force (in kN) exerted by the oil on the gate is 29.43
Answer» A triangular gate with a base width of 2 m and a height of 1.5 m lies in a vertical plane. The top vertex of the gate is 1.5 m below the surface of a tank which contains oil of specific gravity 0.8. Considering the density of water and acceleration due to gravity to be $1000 k g / m^{3}$ and $9.81 m / s^{2}$ respectively, the hydrostatic force (in kN) exerted by the oil on the gate is 29.43

Discussion

8.	Consider a fully developed steady laminar flow of an incompressible fluid with viscosity μ through a circular pipe of radius R. Given that the velocity at a radial location of R/2 from the centerline of the pipe is U1, the shear stress at the wall is KμU1/R, where K is _____2.66
Answer» Consider a fully developed steady laminar flow of an incompressible fluid with viscosity $μ$ through a circular pipe of radius R. Given that the velocity at a radial location of R/2 from the centerline of the pipe is $U_{1}$ , the shear stress at the wall is $K_{μ} U_{1} / R,$ where K is _____ 2.66

Discussion

9.	A circular disc of diameter d is immersed vertically in a liquid of density P. The top most point of the disc just touches the liquid surface. What is the depth of Centre of pressure ?
Answer» A circular disc of diameter d is immersed vertically in a liquid of density P. The top most point of the disc just touches the liquid surface. What is the depth of Centre of pressure ?

Discussion

10.	A particle moves along a curve whose parametric equations are: x=t3+2t, y=−3e−2t and z=2 sin (5t), where x, y and z show variations of the distance covered by the particle (in cm) with time t (in s). The magnitude of the acceleration of the particle (in cm/s2 at t=0) is 12
Answer» A particle moves along a curve whose parametric equations are: $x = t^{3} + 2 t, y = - 3 e^{- 2 t} a n d z = 2 s i n (5 t)$ , where x, y and z show variations of the distance covered by the particle (in cm) with time t (in s). The magnitude of the acceleration of the particle $(i n c m / s^{2} a t t = 0)$ is 12

Discussion

11.	Due to aging of a pipeline, its carrying capacity has decreased by 25%. The corresponding increase in the Darcy Weisbach friction factor, f is %77
Answer» Due to aging of a pipeline, its carrying capacity has decreased by 25%. The corresponding increase in the Darcy Weisbach friction factor, f is % 77

Discussion

12.	At two points 1 and 2 in a pipeline the velocities are V and 2V, respectively. Both the points are at the same elevation. The fluid density is ρ. The flow can be assumed to be incompressible, inviscid, steady and irrotational. The difference in pressures P1 and P2 at points 1 and 2 is
Answer» At two points 1 and 2 in a pipeline the velocities are V and 2V, respectively. Both the points are at the same elevation. The fluid density is $ρ$ . The flow can be assumed to be incompressible, inviscid, steady and irrotational. The difference in pressures P $_{1}$ and P $_{2}$ at points 1 and 2 is

Discussion

13.	A gas flows through a square conduit. At one point along the conduit, the conduit sides are 0.1 m, velocity is 7.55 m/sec and mass density of gas is 1.09 kg/m3. At a second point, the conduit sides are 0.25 m, velocity is 2.02 m/sec. The mass flow rate and density at second point respectively are:
Answer» A gas flows through a square conduit. At one point along the conduit, the conduit sides are 0.1 m, velocity is 7.55 m/sec and mass density of gas is $1.09 k g / m^{3}$ . At a second point, the conduit sides are 0.25 m, velocity is 2.02 m/sec. The mass flow rate and density at second point respectively are:

Discussion

14.	The dimension for kinematic viscosity is
Answer» The dimension for kinematic viscosity is

Discussion

15.	The loss of head at various pipe fittings is given by the expression KV22g. If values of K were 0.40, 0.90, 1.5 and 2.2, then these would correspond respectively to
Answer» The loss of head at various pipe fittings is given by the expression $K \frac{V^{2}}{2 g}$ . If values of K were 0.40, 0.90, 1.5 and 2.2, then these would correspond respectively to

Discussion

16.	The absolute percentage error in the computed discharge over a rectangular weir corresponding to an absolute error of 1.5% in the measurement of head over the sill of the weir would be
Answer» The absolute percentage error in the computed discharge over a rectangular weir corresponding to an absolute error of 1.5% in the measurement of head over the sill of the weir would be

Discussion

17.	Consider the following devices1. orifice 2. Borda's mouthpiece running free3. Bell-mouthed orifice4. External mouthpieceWhat is the correct sequence of these devices by decreasing magnitude of coefficient of discharge?
Answer» Consider the following devices 1. orifice 2. Borda's mouthpiece running free 3. Bell-mouthed orifice 4. External mouthpiece What is the correct sequence of these devices by decreasing magnitude of coefficient of discharge?

17.

Consider the following devices1. orifice 2. Borda's mouthpiece running free3. Bell-mouthed orifice4. External mouthpieceWhat is the correct sequence of these devices by decreasing magnitude of coefficient of discharge?

Answer»

Consider the following devices

1. orifice

2. Borda's mouthpiece running free

3. Bell-mouthed orifice

4. External mouthpiece

What is the correct sequence of these devices by decreasing magnitude of coefficient of discharge?

Discussion

18.	An upward flow of oil (mass density 800 kg/m3, dynamic viscosity 0.8 kg/m-s) takes place under laminar conditions in an inclined pipe of 0.1 m diameter as shown in the figure. The pressures at sections 1 and 2 are measured as p1=435 kN/m2 and p2=200kN/m2.The discharge in the pipe is equal to
Answer» An upward flow of oil (mass density 800 kg/m $^{3},$ dynamic viscosity 0.8 kg/m-s) takes place under laminar conditions in an inclined pipe of 0.1 m diameter as shown in the figure. The pressures at sections 1 and 2 are measured as p $_{1}$ =435 kN/m $^{2}$ and p $_{2}$ =200kN/m $^{2}$ . The discharge in the pipe is equal to

Discussion

19.	Two reservoirs are connected through a 930 m long. 0.3 m diameter pipe, which has a gate valve. The pipe entrance is sharp (loss coefficient = 0.5) and the valve is half-open (loss coefficient = 5.5). The head difference between the two reservoirs is 20 m. Assume the friction factor for the pipe as 0.03 and g=10 m/s2. The discharge in the pipe accounting for all minor and major losses is m3/s0.1414
Answer» Two reservoirs are connected through a 930 m long. 0.3 m diameter pipe, which has a gate valve. The pipe entrance is sharp (loss coefficient = 0.5) and the valve is half-open (loss coefficient = 5.5). The head difference between the two reservoirs is 20 m. Assume the friction factor for the pipe as 0.03 and g=10 m/s $^{2}$ . The discharge in the pipe accounting for all minor and major losses is m $^{3}$ /s 0.1414

19.

Two reservoirs are connected through a 930 m long. 0.3 m diameter pipe, which has a gate valve. The pipe entrance is sharp (loss coefficient = 0.5) and the valve is half-open (loss coefficient = 5.5). The head difference between the two reservoirs is 20 m. Assume the friction factor for the pipe as 0.03 and g=10 m/s2. The discharge in the pipe accounting for all minor and major losses is m3/s0.1414

Answer»

Two reservoirs are connected through a 930 m long. 0.3 m diameter pipe, which has a gate valve. The pipe entrance is sharp (loss coefficient = 0.5) and the valve is half-open (loss coefficient = 5.5). The head difference between the two reservoirs is 20 m. Assume the friction factor for the pipe as 0.03 and g=10 m/s $^{2}$ . The discharge in the pipe accounting for all minor and major losses is m $^{3}$ /s

0.1414

Discussion

20.	The horizontal and vertical hydrostatic forces Fx and Fy on the semicircular gate, having a width w into the plane of figure,are
Answer» The horizontal and vertical hydrostatic forces $F_{x}$ and $F_{y}$ on the semicircular gate, having a width w into the plane of figure,are

Discussion

21.	For a fully developed laminar flow of water (dynamic viscosity 0.001 Pa-s) through a pipe radius 5 cm, the axial pressure gradient is -10 Pa/m. The magnitude of axial velocity (in m/s) at a radial location of 0.2 cm is___________6.24
Answer» For a fully developed laminar flow of water (dynamic viscosity 0.001 Pa-s) through a pipe radius 5 cm, the axial pressure gradient is -10 Pa/m. The magnitude of axial velocity (in m/s) at a radial location of 0.2 cm is___________ 6.24

Discussion

22.	The velocity distribution in the boundary layer is given by uU=yδ, where u is the velocity at a distance of y from the boundary and u=U at y=δ,δ being boundary layer thickness. Then the value of momentum thickness will be
Answer» The velocity distribution in the boundary layer is given by $\frac{u}{U} = \frac{y}{δ},$ where u is the velocity at a distance of y from the boundary and u=U at y= $δ, δ$ being boundary layer thickness. Then the value of momentum thickness will be

Discussion

23.	The x component of velocity in a two dimensional incompressible flow is given by u=1.5x. At the point (x, y) = (1, 0), the y component of velocity v = 0. The equation for the y component of velocity is
Answer» The x component of velocity in a two dimensional incompressible flow is given by $u = 1.5 x$ . At the point (x, y) = (1, 0), the y component of velocity v = 0. The equation for the y component of velocity is

Discussion

24.	Consider the two-dimensional velocity field given by →V=(5+a1x++b1y)^i+(4+a2x+b2y)^j where a1,b1,a2 and b2 are constants. Which one of the following conditions needs to be satisfied for the flow to be incompressible?
Answer» Consider the two-dimensional velocity field given by $\to V = (5 + a_{1} x + + b_{1} y)^i + (4 + a_{2} x + b_{2} y)^j$ where $a_{1}, b_{1}, a_{2} a n d b_{2}$ are constants. Which one of the following conditions needs to be satisfied for the flow to be incompressible?

Discussion

25.	A 1 : 50 scale model of a spillway is to be tested in the laboratory. The discharge in the prototype is 1000m3/s. The discharge to be maintained in the model test is
Answer» A 1 : 50 scale model of a spillway is to be tested in the laboratory. The discharge in the prototype is $1000 m^{3} / s$ . The discharge to be maintained in the model test is

Discussion

26.	Two pipes of diameters d1 and d2 converge to form a pipe of diameter d. If the fluid flows with a velocity of v1 and v2 in the two pipes, what will be the flow velocity in the third pipe ?
Answer» Two pipes of diameters $d_{1}$ and $d_{2}$ converge to form a pipe of diameter d. If the fluid flows with a velocity of $v_{1}$ and $v_{2}$ in the two pipes, what will be the flow velocity in the third pipe ?

Discussion

27.	A body moving through still water at 8 m/s produces a water velocity of 5 m/sec at a point 1 m ahead. The difference in pressure between the nose and the point 1 m ahead would be
Answer» A body moving through still water at 8 m/s produces a water velocity of 5 m/sec at a point 1 m ahead. The difference in pressure between the nose and the point 1 m ahead would be

Discussion

28.	In fully developed laminar flow in a circular pipe, if the velocity at midway between the wall surface and the centerline is measured to be 6 m/s, then the velocity at the centre of pipe is
Answer» In fully developed laminar flow in a circular pipe, if the velocity at midway between the wall surface and the centerline is measured to be 6 m/s, then the velocity at the centre of pipe is

Discussion

29.	In steady laminar flow of a liquid through a circular pipe of internal diameter D, carrying a constant discharge, the hydraulic gradient is inversely proportional to
Answer» In steady laminar flow of a liquid through a circular pipe of internal diameter D, carrying a constant discharge, the hydraulic gradient is inversely proportional to

Discussion

30.	The velocity profile in fully developed laminar flow in a pipe of diameter D is given by u=u0(1−4r2/D2), where r is the radial distance from the center. If the viscosity of the fluid is μ, the pressure drop across a length L of the pipe is
Answer» The velocity profile in fully developed laminar flow in a pipe of diameter D is given by $u = u_{0} (1 - 4 r^{2} / D^{2})$ , where r is the radial distance from the center. If the viscosity of the fluid is $μ$ , the pressure drop across a length L of the pipe is

Discussion

31.	An aircraft is flying in level flight at a speed of 200 km/hr through air (density, ρ=1.2 kg/m3, and viscosity μ=1.6×10−5 Ns/m2). The lift coefficient at this speed is 0.4 and the drag coefficient is 0.0065. The mass of the aircraft is 800 kg. The effective lift area of the aircraft is
Answer» An aircraft is flying in level flight at a speed of 200 km/hr through air (density, $ρ = 1.2 k g / m^{3}$ , and viscosity $μ = 1.6 \times 10^{- 5} N s / m^{2}$ ). The lift coefficient at this speed is 0.4 and the drag coefficient is 0.0065. The mass of the aircraft is 800 kg. The effective lift area of the aircraft is

Discussion

32.	A solid cylinder of length L, diameter D and specific gravity 0.6 floats in neutral equilibrium in water with its axis vertical. What is the ratio of L to D?
Answer» A solid cylinder of length L, diameter D and specific gravity 0.6 floats in neutral equilibrium in water with its axis vertical. What is the ratio of L to D?

Discussion

33.	If H is the head over the crest of a rectangular weir, the discharge varies as:
Answer» If H is the head over the crest of a rectangular weir, the discharge varies as:

Discussion

34.	A depth-discharge relationship of the canal section is maintained at a notch fall because the sill of the notches is
Answer» A depth-discharge relationship of the canal section is maintained at a notch fall because the sill of the notches is

Discussion

35.	A venturimeter, having a diameter of 7.5 cm at the throat and 15 cm at the enlarged end, is installed in a horizontal pipeline of 15 cm diameter. The pipe carries an incompressible fluid at a steady rate of 30 litres per second. The difference of pressure head measured in terms of the moving fluid in between the enlarged and the throat of the venturimeter is observed to be 2.45 m. Taking the acceleration due to gravity as 9.81 m/s2, the coefficient of discharge of the venturimeter (correct up to two places of decimal) is 0.95
Answer» A venturimeter, having a diameter of 7.5 cm at the throat and 15 cm at the enlarged end, is installed in a horizontal pipeline of 15 cm diameter. The pipe carries an incompressible fluid at a steady rate of 30 litres per second. The difference of pressure head measured in terms of the moving fluid in between the enlarged and the throat of the venturimeter is observed to be 2.45 m. Taking the acceleration due to gravity as 9.81 m/s $^{2}$ , the coefficient of discharge of the venturimeter (correct up to two places of decimal) is 0.95

Discussion

36.	If ρ is density of fluid, then pressure of fluid due to water hammer is directly proportional to-
Answer» $If ρ is density of fluid, then pressure of fluid due to water hammer is directly proportional to-$

Discussion

37.	The barrier shown between two water tanks of unit width (1 m) into the plane of the screen is modeled as a cantilever.Taking the density of water as 1000kg/m3 and the acceleration due to gravity as 10m/s2, the maximum absolute bending moment developed in the cantilever is __kNm (round off to the nearest integer)105
Answer» The barrier shown between two water tanks of unit width (1 m) into the plane of the screen is modeled as a cantilever. Taking the density of water as $1000 k g / m^{3}$ and the acceleration due to gravity as $10 m / s^{2}$ , the maximum absolute bending moment developed in the cantilever is __kNm (round off to the nearest integer) 105

Discussion

38.	Water is pumped at a steady uniform flow rate of 0.01 m3/s through a horizontal smooth circular pipe of 100 mm diameter. Given that the Reynolds number is 800 and g is 9.81 m/s2, the head loss (in meters, up to one decimal place) per km length due to friction would be66.11
Answer» Water is pumped at a steady uniform flow rate of 0.01 m $^{3}$ /s through a horizontal smooth circular pipe of 100 mm diameter. Given that the Reynolds number is 800 and g is 9.81 m/s $^{2}$ , the head loss (in meters, up to one decimal place) per km length due to friction would be 66.11

38.

Water is pumped at a steady uniform flow rate of 0.01 m3/s through a horizontal smooth circular pipe of 100 mm diameter. Given that the Reynolds number is 800 and g is 9.81 m/s2, the head loss (in meters, up to one decimal place) per km length due to friction would be66.11

Answer»

Water is pumped at a steady uniform flow rate of 0.01 m $^{3}$ /s through a horizontal smooth circular pipe of 100 mm diameter. Given that the Reynolds number is 800 and g is 9.81 m/s $^{2}$ , the head loss (in meters, up to one decimal place) per km length due to friction would be

66.11

Discussion

39.	Which one of the following expresses the height of rise or fall of a liquid in a capillary tube?Where, w = Specific weight of the liquidα = Angle of contact of the liquid surfaceσ = Surface tension
Answer» Which one of the following expresses the height of rise or fall of a liquid in a capillary tube? Where, w = Specific weight of the liquid $α$ = Angle of contact of the liquid surface $σ$ = Surface tension

Discussion

40.	An 1:50 model of an ogee spillway crest records an acceleration of 1.5m/sec2 at a certain location. The homologous value of acceleration in the prototype is 1.5
Answer» An 1:50 model of an ogee spillway crest records an acceleration of $1.5 m / s e c^{2}$ at a certain location. The homologous value of acceleration in the prototype is 1.5

Discussion

41.	If in a turbulent boundary layer the velocity distribution is assumed to be given by u∝y1/4, then the boundary layer thickness varies with longitudinal distance X as
Answer» If in a turbulent boundary layer the velocity distribution is assumed to be given by $u \propto y^{1 / 4}$ , then the boundary layer thickness varies with longitudinal distance X as

Discussion

42.	The head loss due to sudden expansion is expressed by
Answer» The head loss due to sudden expansion is expressed by

Discussion

43.	Three reservoirs A, B and C are interconnected by pipes as shown in the figure. Water surface elevations in the reservoirs and the Piezometric head at the junction f are indicated in the figure.Discharges Q1,Q2 and Q3 are related as
Answer» Three reservoirs A, B and C are interconnected by pipes as shown in the figure. Water surface elevations in the reservoirs and the Piezometric head at the junction f are indicated in the figure. Discharges Q $_{1}$ ,Q $_{2}$ and Q $_{3}$ are related as

Discussion

44.	Air discharge steadily through a horizontal nozzle and impinges on a stationary vertical plate as shown in the figureThe inlet and outlet areas of the nozzle are 0.1 m2 and 0.02 m2, respectively. Take air density as constant and equal to 1.2 kg/m3. If the inlet gauge pressure of air is 0.36 kPa, the gauge pressure at point O on the plate is_____ kPa (round off to two decimal places).0.375
Answer» Air discharge steadily through a horizontal nozzle and impinges on a stationary vertical plate as shown in the figure The inlet and outlet areas of the nozzle are 0.1 $m^{2}$ and 0.02 $m^{2}$ , respectively. Take air density as constant and equal to 1.2 kg/ $m^{3}$ . If the inlet gauge pressure of air is 0.36 kPa, the gauge pressure at point O on the plate is_____ kPa (round off to two decimal places). 0.375

Discussion

45.	With reference to a standard Cartesian (x, y) plane, the parabolic velocity distribution profile of fully developed laminar flow in x-direction between two parallel, stationary and identical plates that are seperated by distance h, is given by the expressionu=−h28μdpdx[1−4(yh)2]In this equation, the y = 0 axis lies equidistant between the plates at a distance h/2 from the two plates, p is the pressure variable and μ is the dynamic viscosity term. The maximum and average velocities are, respectively
Answer» With reference to a standard Cartesian (x, y) plane, the parabolic velocity distribution profile of fully developed laminar flow in x-direction between two parallel, stationary and identical plates that are seperated by distance h, is given by the expression $u = - \frac{h^{2}}{8 μ} \frac{d p}{d x} [1 - 4 {(\frac{y}{h})}^{2}]$ In this equation, the y = 0 axis lies equidistant between the plates at a distance h/2 from the two plates, p is the pressure variable and $μ$ is the dynamic viscosity term. The maximum and average velocities are, respectively

Discussion

46.	Group-I Contains dimensionless parameter and Group-II contains ratio Group-IP. Mach numberQ. Reynold numberR. Weber numberS. Froude number Group-II1. Ratio of inertial force and gravity force. 2. Ratio of fluid velocity and velocity of sound.3. Ratio of inertial force and viscous force.4. Ratio of inertial force and surface tension force.Correct match of the dimensionless parameter in Group-I with Group-II is P Q R S
Answer» Group-I Contains dimensionless parameter and Group-II contains ratio Group-I P. Mach number Q. Reynold number R. Weber number S. Froude number Group-II 1. Ratio of inertial force and gravity force. 2. Ratio of fluid velocity and velocity of sound. 3. Ratio of inertial force and viscous force. 4. Ratio of inertial force and surface tension force. Correct match of the dimensionless parameter in Group-I with Group-II is P Q R S

Discussion

47.	A 50 cm high, 30 cm x 30 cm tank is filled with oil having specific gravity 0.8 upto a depth of 30 cm, what is the maximum acceleration to which tank may be translated on a level road without spilling the oil ? (g=9.81 m/sec2)
Answer» A 50 cm high, 30 cm x 30 cm tank is filled with oil having specific gravity 0.8 upto a depth of 30 cm, what is the maximum acceleration to which tank may be translated on a level road without spilling the oil ? ( $g = 9.81 m / s e c^{2}$ )

Discussion

48.	A solid sphere (diameter 6 mm) is rising through oil (mass density 900 kg/m3, dynamic viscosity 0.7 kg/m−s) at a constant velocity of 1 cm/s. What is the specific weight of the material from which the sphere is made? (Take g=9.81m/s2)
Answer» A solid sphere (diameter 6 mm) is rising through oil (mass density $900 k g / m^{3}$ , dynamic viscosity $0.7 k g / m - s$ ) at a constant velocity of 1 cm/s. What is the specific weight of the material from which the sphere is made? (Take $g = 9.81 m / s^{2}$ )

Discussion

49.	In order to estimate the energy loss in a pipeline of 1 m diameter through which kerosene of specific gravity 0.80 and dynamic viscosity 0.02 poise is to be transported at the rate of 1 m3/s, model tests were conducted on a 0.1 m diameter pipe using water at 20∘C is 1.00 ×10−2 Poise, then the discharge required for the model pipe would be
Answer» In order to estimate the energy loss in a pipeline of 1 m diameter through which kerosene of specific gravity 0.80 and dynamic viscosity 0.02 poise is to be transported at the rate of 1 $m^{3} / s$ , model tests were conducted on a 0.1 m diameter pipe using water at $20^{\circ} C$ is 1.00 $\times 10^{- 2}$ Poise, then the discharge required for the model pipe would be

Discussion

50.	For the laminar flow of water over a sphere, the drag coefficient CF is defined as CF=F/(ρU2D2), where F is the drag force, ρ is the fluid density, U is the fluid velocity and D is the diameter of the sphere. The density of water is 1000 kg/m3. When the diameter of the sphere is 100 mm and the fluid velocity is 2 m/s, the drag coefficient is 0.5. If water now flows over another sphere of diameter 200 mm under dynamically similar conditions, the drag force (in N) on this sphere is_______20
Answer» For the laminar flow of water over a sphere, the drag coefficient $C_{F}$ is defined as $C_{F} = F / (ρ U^{2} D^{2})$ , where F is the drag force, $ρ$ is the fluid density, U is the fluid velocity and D is the diameter of the sphere. The density of water is 1000 kg/ $m^{3}$ . When the diameter of the sphere is 100 mm and the fluid velocity is 2 m/s, the drag coefficient is 0.5. If water now flows over another sphere of diameter 200 mm under dynamically similar conditions, the drag force (in N) on this sphere is_______ 20

Discussion

Explore topic-wise InterviewSolutions in .

The head over a V-notch at the end of a channel is 75 cm. If an error of 0.15 cm is possible In the measurement of the head, then the percentage error in computing the discharge is

What is the momentum thickness for the boundary layer with velocity distribution uU=yδ?

The velocity field of an incompressible flow is given byV= (a1x+a2y+a3z)i+(b1x+b2y+b3z)j+(c1x+c2y+c3z)k, where a1=2 and c3=−4. The value of b2 is______2

For a two-dimensional irrotational flow, the velocity potential is defined as ϕ=loge (x2+y2). Which of the following is a possible stream function, ψ, for this flow?

For accurate flow measurement in open channels, an arrangement for aeration under the nappe is necessary when the weir used is

Consider a fully developed steady laminar flow of an incompressible fluid with viscosity μ through a circular pipe of radius R. Given that the velocity at a radial location of R/2 from the centerline of the pipe is U1, the shear stress at the wall is KμU1/R, where K is _____2.66

A circular disc of diameter d is immersed vertically in a liquid of density P. The top most point of the disc just touches the liquid surface. What is the depth of Centre of pressure ?

A particle moves along a curve whose parametric equations are: x=t3+2t, y=−3e−2t and z=2 sin (5t), where x, y and z show variations of the distance covered by the particle (in cm) with time t (in s). The magnitude of the acceleration of the particle (in cm/s2 at t=0) is 12

Due to aging of a pipeline, its carrying capacity has decreased by 25%. The corresponding increase in the Darcy Weisbach friction factor, f is %77

At two points 1 and 2 in a pipeline the velocities are V and 2V, respectively. Both the points are at the same elevation. The fluid density is ρ. The flow can be assumed to be incompressible, inviscid, steady and irrotational. The difference in pressures P1 and P2 at points 1 and 2 is

A gas flows through a square conduit. At one point along the conduit, the conduit sides are 0.1 m, velocity is 7.55 m/sec and mass density of gas is 1.09 kg/m3. At a second point, the conduit sides are 0.25 m, velocity is 2.02 m/sec. The mass flow rate and density at second point respectively are:

The dimension for kinematic viscosity is

The loss of head at various pipe fittings is given by the expression KV22g. If values of K were 0.40, 0.90, 1.5 and 2.2, then these would correspond respectively to

The absolute percentage error in the computed discharge over a rectangular weir corresponding to an absolute error of 1.5% in the measurement of head over the sill of the weir would be

Consider the following devices1. orifice 2. Borda's mouthpiece running free3. Bell-mouthed orifice4. External mouthpieceWhat is the correct sequence of these devices by decreasing magnitude of coefficient of discharge?

An upward flow of oil (mass density 800 kg/m3, dynamic viscosity 0.8 kg/m-s) takes place under laminar conditions in an inclined pipe of 0.1 m diameter as shown in the figure. The pressures at sections 1 and 2 are measured as p1=435 kN/m2 and p2=200kN/m2.The discharge in the pipe is equal to

The horizontal and vertical hydrostatic forces Fx and Fy on the semicircular gate, having a width w into the plane of figure,are

For a fully developed laminar flow of water (dynamic viscosity 0.001 Pa-s) through a pipe radius 5 cm, the axial pressure gradient is -10 Pa/m. The magnitude of axial velocity (in m/s) at a radial location of 0.2 cm is___________6.24

The velocity distribution in the boundary layer is given by uU=yδ, where u is the velocity at a distance of y from the boundary and u=U at y=δ,δ being boundary layer thickness. Then the value of momentum thickness will be

The x component of velocity in a two dimensional incompressible flow is given by u=1.5x. At the point (x, y) = (1, 0), the y component of velocity v = 0. The equation for the y component of velocity is

Consider the two-dimensional velocity field given by →V=(5+a1x++b1y)^i+(4+a2x+b2y)^j where a1,b1,a2 and b2 are constants. Which one of the following conditions needs to be satisfied for the flow to be incompressible?

A 1 : 50 scale model of a spillway is to be tested in the laboratory. The discharge in the prototype is 1000m3/s. The discharge to be maintained in the model test is

Two pipes of diameters d1 and d2 converge to form a pipe of diameter d. If the fluid flows with a velocity of v1 and v2 in the two pipes, what will be the flow velocity in the third pipe ?

A body moving through still water at 8 m/s produces a water velocity of 5 m/sec at a point 1 m ahead. The difference in pressure between the nose and the point 1 m ahead would be

In fully developed laminar flow in a circular pipe, if the velocity at midway between the wall surface and the centerline is measured to be 6 m/s, then the velocity at the centre of pipe is

In steady laminar flow of a liquid through a circular pipe of internal diameter D, carrying a constant discharge, the hydraulic gradient is inversely proportional to

The velocity profile in fully developed laminar flow in a pipe of diameter D is given by u=u0(1−4r2/D2), where r is the radial distance from the center. If the viscosity of the fluid is μ, the pressure drop across a length L of the pipe is

An aircraft is flying in level flight at a speed of 200 km/hr through air (density, ρ=1.2 kg/m3, and viscosity μ=1.6×10−5 Ns/m2). The lift coefficient at this speed is 0.4 and the drag coefficient is 0.0065. The mass of the aircraft is 800 kg. The effective lift area of the aircraft is

A solid cylinder of length L, diameter D and specific gravity 0.6 floats in neutral equilibrium in water with its axis vertical. What is the ratio of L to D?

If H is the head over the crest of a rectangular weir, the discharge varies as:

A depth-discharge relationship of the canal section is maintained at a notch fall because the sill of the notches is

If ρ is density of fluid, then pressure of fluid due to water hammer is directly proportional to-

Water is pumped at a steady uniform flow rate of 0.01 m3/s through a horizontal smooth circular pipe of 100 mm diameter. Given that the Reynolds number is 800 and g is 9.81 m/s2, the head loss (in meters, up to one decimal place) per km length due to friction would be66.11

Which one of the following expresses the height of rise or fall of a liquid in a capillary tube?Where, w = Specific weight of the liquidα = Angle of contact of the liquid surfaceσ = Surface tension

An 1:50 model of an ogee spillway crest records an acceleration of 1.5m/sec2 at a certain location. The homologous value of acceleration in the prototype is 1.5

If in a turbulent boundary layer the velocity distribution is assumed to be given by u∝y1/4, then the boundary layer thickness varies with longitudinal distance X as

The head loss due to sudden expansion is expressed by

Three reservoirs A, B and C are interconnected by pipes as shown in the figure. Water surface elevations in the reservoirs and the Piezometric head at the junction f are indicated in the figure.Discharges Q1,Q2 and Q3 are related as

A 50 cm high, 30 cm x 30 cm tank is filled with oil having specific gravity 0.8 upto a depth of 30 cm, what is the maximum acceleration to which tank may be translated on a level road without spilling the oil ? (g=9.81 m/sec2)

A solid sphere (diameter 6 mm) is rising through oil (mass density 900 kg/m3, dynamic viscosity 0.7 kg/m−s) at a constant velocity of 1 cm/s. What is the specific weight of the material from which the sphere is made? (Take g=9.81m/s2)