The hydrodynamic and thermal boundary layers will merge, when (A) Prandtl number is one (B) Schmidt number tends to infinity (C) Nusselt number tends to infinity (D) Archimedes number is greater than 10000

The hydrodynamic and thermal boundary layers will merge, when
(A) Prandtl number is one
(B) Schmidt number tends to infinity
(C) Nusselt number tends to infinity
(D) Archimedes number is greater than 10000
by

1 Answer

Answer :

(A) Prandtl number is one
by

Related questions

. If Prandtl number is greater than the Schmidt number, then the (A) Thermal boundary layer lies inside the concentration boundary layer (B) Concentration boundary layer lies inside the thermal boundary layer (C) Thermal & concentration boundary layers are of equal thickness (D) Hydrodynamic (i.e., momentum) boundary layer is thicker than the other two

Description : . If Prandtl number is greater than the Schmidt number, then the (A) Thermal boundary layer lies inside the concentration boundary layer (B) Concentration boundary layer lies inside the thermal boundary ... (D) Hydrodynamic (i.e., momentum) boundary layer is thicker than the other two

Last Answer : (A) Thermal boundary layer lies inside the concentration boundary layer

At what value of Prandtl number, the hydrodynamic and thermal boundary layers of a fluid flowing over a heated plate will be identical? (A) 1 (B) < 1 (C) > 1 (D) None of these

Description : At what value of Prandtl number, the hydrodynamic and thermal boundary layers of a fluid flowing over a heated plate will be identical? (A) 1 (B) < 1 (C) > 1 (D) None of these

Last Answer : (A) 1

Pick out the wrong statement. (A) In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapour feed (B) In small columns, local efficiency is larger than Murphree efficiency; in large columns local efficiency is smaller than Murphree efficiency (C) For Laminar flow over a plate of length L, the local mass transfer co￾efficient at a distance L from the leading edge is 1.5 × 10 -2m/s. Then the average mass transfer co-efficient for the plate is 2 × 10 -2m/s (D) The concentration and hydrodynamic boundary layers over a flat plate are of equal thickness, if Schmidt number is equal to unity

Description : Pick out the wrong statement. (A) In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapour feed (B) In ... layers over a flat plate are of equal thickness, if Schmidt number is equal to unity

Last Answer : (C) For Laminar flow over a plate of length L, the local mass transfer co￾efficient at a distance L from the leading edge is 1.5 × 10 -2m/s. Then the average mass transfer co-efficient for the plate is 2 × 10 -2m/s

Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations. (A) Sherwood number in mass transfer is analogous to Nusselt number in heat transfer (B) Prandtl number in heat transfer is analogous to Schmidt number in mass transfer (C) Reynolds number in mass transfer is analogous to Grashoff number in heat transfer (D) Reynolds number remains the same in both heat and mass transfer

Description : Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations. (A) Sherwood number in mass transfer is analogous to Nusselt number in heat transfer ... heat transfer (D) Reynolds number remains the same in both heat and mass transfer

Last Answer : (C) Reynolds number in mass transfer is analogous to Grashoff number in heat transfer

Pick out the wrong statement. (A) In drying a solid containing moisture above the critical moisture content the number of degrees of freedom is 2 (B) Sherwood number in mass transfer corresponds to Nusselt number in heat transfer and Schmidt number to Prandtl number (C) Forced convection is relatively more effective in increasing the rate of mass transfer, if Schmidt number is larger (D) Hot gases at moderate pressure are usually in the shell side of shell and tube heat exchangers. At higher pressure, however, it is customary to put gas in the tube side

Description : Pick out the wrong statement. (A) In drying a solid containing moisture above the critical moisture content the number of degrees of freedom is 2 (B) Sherwood number in mass transfer corresponds to ... tube heat exchangers. At higher pressure, however, it is customary to put gas in the tube side

Last Answer : (C) Forced convection is relatively more effective in increasing the rate of mass transfer, if Schmidt number is larger

The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is (A) Nusselt number (B) Sherwood number (C) Schmidt number (D) Stanton numbe

Description : The dimensionless group in mass transfer that is equivalent to Prandtl number in heat transfer is (A) Nusselt number (B) Sherwood number (C) Schmidt number (D) Stanton numbe

Last Answer : (C) Schmidt number

The non-dimensional temperature gradient in a liquid at the wall of a pipe is the (A) Heat flux (B) Nusselt number (C) Prandtl number (D) Schmidt number

Description : The non-dimensional temperature gradient in a liquid at the wall of a pipe is the (A) Heat flux (B) Nusselt number (C) Prandtl number (D) Schmidt number

Last Answer : (A) Heat flux

Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is (A) 1 (B) < 1 (C) > 1 (D) > 5

Description : Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is (A) 1 (B) < 1 (C) > 1 (D) > 5

Last Answer : (B) < 1

For flow over a flat plate, the ratio of thermal boundary layer thickness, 'xt' and hydrodynamic boundary layer thickness 'x' is equal to (where, NPr = Prandtl number) (A) NPr (B) NPr 1/3 (C) NPr -1 (D) NPr -1/3

Description : For flow over a flat plate, the ratio of thermal boundary layer thickness, 'xt' and hydrodynamic boundary layer thickness 'x' is equal to (where, NPr = Prandtl number) (A) NPr (B) NPr 1/3 (C) NPr -1 (D) NPr -1/3

Last Answer : (B) NPr 1/3

The thermal boundary layer at NPr > 1 (A) Is thicker than hydrodynamic boundary layer (B) Is thinner than hydrodynamic boundary layer (C) And the hydrodynamic boundary layers are identical (D) Disappears

Description : The thermal boundary layer at NPr > 1 (A) Is thicker than hydrodynamic boundary layer (B) Is thinner than hydrodynamic boundary layer (C) And the hydrodynamic boundary layers are identical (D) Disappears

Last Answer : (B) Is thinner than hydrodynamic boundary layer

The ratio of momentum diffusivity to thermal diffusivity is the __________ number. (A) Prandtl (B) Nusselt (C) Stanton (D) Grashoff

Description : The ratio of momentum diffusivity to thermal diffusivity is the __________ number. (A) Prandtl (B) Nusselt (C) Stanton (D) Grashoff

Last Answer : (A) Prandtl

The ratio of kinematic viscosity to thermal diffusivity is called the __________ number. (A) Peclet (B) Prandtl (C) Stanton (D) Nusselt

Description : The ratio of kinematic viscosity to thermal diffusivity is called the __________ number. (A) Peclet (B) Prandtl (C) Stanton (D) Nusselt

Last Answer : (B) Prandtl

Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the __________ number. (A) Sherwood (B) Schmidt (C) Peclet (D) Stanton

Description : Corresponding to Nusselt number in heat transfer, the dimensionless group in mass transfer is the __________ number. (A) Sherwood (B) Schmidt (C) Peclet (D) Stanton

Last Answer : (A) Sherwood

The ratio of hydrodynamic boundary layer to thermal boundary layer thickness in case of liquid metals is (A) < 1 (B) 1 (C) > 1 (D) 2

Description : The ratio of hydrodynamic boundary layer to thermal boundary layer thickness in case of liquid metals is (A) < 1 (B) 1 (C) > 1 (D) 2

Last Answer : (A) < 1

Nusselt number (for forced convection heat transfer) is a function of the __________ number. (A) Prandtl (B) Reynolds (C) Both (A) & (B) (D) Neither (A) nor (B)

Description : Nusselt number (for forced convection heat transfer) is a function of the __________ number. (A) Prandtl (B) Reynolds (C) Both (A) & (B) (D) Neither (A) nor (B)

Last Answer : (C) Both (A) & (B)

jH factor for heat transfer depends upon the __________ number. (A) Biot (B) Nusselt (C) Reynolds (D) Prandtl

Description : jH factor for heat transfer depends upon the __________ number. (A) Biot (B) Nusselt (C) Reynolds (D) Prandtl

Last Answer : (C) Reynolds

Nusselt number is a function of Prandtl number and __________ number of fluid in natural convection heat transfer. (A) Grashoff (B) Biot (C) Stanton

Description : Nusselt number is a function of Prandtl number and __________ number of fluid in natural convection heat transfer. (A) Grashoff (B) Biot (C) Stanton

Last Answer : (A) Grashoff

Cpµ/K is termed as the __________ number. (A) Grashoff (B) Nusselt (C) Prandtl (D) Stanton

Description : Cpµ/K is termed as the __________ number. (A) Grashoff (B) Nusselt (C) Prandtl (D) Stanton

Last Answer : (C) Prandtl

Corresponding to Prandtl number in heat transfer, the dimensionless group in mass transfer is the __________ number. (A) Schmidt (B) Sherwood (C) Peclet (D) Stanton

Description : Corresponding to Prandtl number in heat transfer, the dimensionless group in mass transfer is the __________ number. (A) Schmidt (B) Sherwood (C) Peclet (D) Stanton

Last Answer : (A) Schmidt

Which of the following plays an important role in problems of simultaneous heat and mass transfer?(A) Lewis number (B) Schmidt number (C) Prandtl number (D) Sherwood number

Description : Which of the following plays an important role in problems of simultaneous heat and mass transfer (A) Lewis number (B) Schmidt number (C) Prandtl number (D) Sherwood number

Last Answer : (A) Lewis number

How the thickness of thermal boundary layer and thickness of hydrodynamic boundary layer related ?

Description : How the thickness of thermal boundary layer and thickness of hydrodynamic boundary layer related ?

Last Answer : Ratio of their thickness = (Prandtl number)-1/3.

Give expression for the following and explain the terms involved. (i) Nusselt number (ii) Prandtl number

Description : Give expression for the following and explain the terms involved. (i) Nusselt number (ii) Prandtl number

Last Answer : 1. Nusselt NumberNNU= hd/k  h – fim heat transfer coefficient  d - diameter of pipe  k – thermal conductivity of fluid 2. Prandtl Number NPR -Cp µ/k Cp– specific heat of fluid µ - viscosity of fluid  k – thermal conductivity

In hydrodynamic lubrication, film thickness remains unaffected by change in speeds. a) True b) Increase with increase in speed c) Decrease with increase in speed d) Disappear as the speed tends to infinty

Description : In hydrodynamic lubrication, film thickness remains unaffected by change in speeds. a) True b) Increase with increase in speed c) Decrease with increase in speed d) Disappear as the speed tends to infinty

Last Answer : b) Increase with increase in speed

Gibbs free energy of a pure fluid approaches __________ as the pressure tends to zero at constant temperature. (A) Infinity (B) Minus infinity (C) Zero (D) None of these

Description : Gibbs free energy of a pure fluid approaches __________ as the pressure tends to zero at constant temperature. (A) Infinity (B) Minus infinity (C) Zero (D) None of these

Last Answer : (B) Minus infinity

The length of the tube necessary for the boundary layer to reach thecentre of the tube and for fully developed flow to be established is called the__________ length.(A) Equivalent(B) Transition(C) Prandtl mixing(D) None of these

Description : The length of the tube necessary for the boundary layer to reach thecentre of the tube and for fully developed flow to be established is called the __________ length. (A) Equivalent (B) Transition (C) Prandtl mixing (D) None of these

Last Answer : (B) Transition

The major reason of hydrodynamic noise (i.e., noise resulting from liquid flow) is (A) Pipe vibrations (B) Cavitation (C) Boundary layer separation (D) Fluctuation in liquid flow

Description : The major reason of hydrodynamic noise (i.e., noise resulting from liquid flow) is (A) Pipe vibrations (B) Cavitation (C) Boundary layer separation (D) Fluctuation in liquid flow

Last Answer : (B) Cavitation

Starting friction is low in case of the __________ lubrication. (A) Boundary (B) Hydrodynamic (C) Hydrostatic (D) Mixed/semi-fluid

Description : Starting friction is low in case of the __________ lubrication. (A) Boundary (B) Hydrodynamic (C) Hydrostatic (D) Mixed/semi-fluid

Last Answer : (C) Hydrostatic

Pick out the wrong statement. (A) Mechanical agitation is required, if the system has low interfacial tension (B) Sieve tray towers are generally used for systems having low interfacial tension (C) When Henry's law constant is very small, then the mass transfer rate is controlled by the gas film resistance (D) Taylor-Prandtl analogy for heat and mass transfer considers the transfer through both laminar and turbulent layers

Description : Pick out the wrong statement. (A) Mechanical agitation is required, if the system has low interfacial tension (B) Sieve tray towers are generally used for systems having low ... Prandtl analogy for heat and mass transfer considers the transfer through both laminar and turbulent layers

Last Answer : (A) Mechanical agitation is required, if the system has low interfacial tension

Nusselt number/Biot number varies (A) Inversely with thermal conductivity (B) Directly with heat transfer co-efficient (C) Directly with thermal conductivity (D) Inversely with the dimension of the solid

Description : Nusselt number/Biot number varies (A) Inversely with thermal conductivity (B) Directly with heat transfer co-efficient (C) Directly with thermal conductivity (D) Inversely with the dimension of the solid

Last Answer : (A) Inversely with thermal conductivity

When the number of sides of a polygon tends to infinity, it approaches _______.

Description : When the number of sides of a polygon tends to infinity, it approaches _______.

Last Answer : When the number of sides of a polygon tends to infinity, it approaches _______.

In physical terms, Schmidt number means (A) Thermal diffusivity/mass diffusivity(B) Thermal diffusivity/momentum diffusivity(C) Momentum diffusivity/mass diffusivity(D) Mass diffusivity/thermal diffusivity

Description : In physical terms, Schmidt number means (A) Thermal diffusivity/mass diffusivity (B) Thermal diffusivity/momentum diffusivity (C) Momentum diffusivity/mass diffusivity (D) Mass diffusivity/thermal diffusivity

Last Answer : (C) Momentum diffusivity/mass diffusivity

The Schmidt number which is defined as, μ/ρ D, is the ratio of the (A) Momentum diffusivity to the mass diffusivity (B) Thermal diffusivity to the mass diffusivity (C) Momentum diffusivity to the thermal diffusivity (D) None of these

Description : The Schmidt number which is defined as, μ/ρ D, is the ratio of the (A) Momentum diffusivity to the mass diffusivity (B) Thermal diffusivity to the mass diffusivity (C) Momentum diffusivity to the thermal diffusivity (D) None of these

Last Answer : (A) Momentum diffusivity to the mass diffusivity

Boundary lubricated bearing is (A) Thick film bearing (B) Thin film bearing (C) Hydrodynamic bearing (D) Hydrostatic bearing

Description : Boundary lubricated bearing is (A) Thick film bearing (B) Thin film bearing (C) Hydrodynamic bearing (D) Hydrostatic bearing

Last Answer : (B) Thin film bearing

02. The separation of flow occurs when the hydrodynamic boundary layer thickness is reduced to zero. A) AgreeB) Disagree

Description : 02. The separation of flow occurs when the hydrodynamic boundary layer thickness is reduced to zero. A) Agree B) Disagree

Last Answer : A

Prandtl number is the ratio of (A) Mass diffusivity to thermal diffusivity (B) Momentum diffusivity to thermal diffusivity (C) Thermal diffusivity to mass diffusivity (D) Thermal diffusivity to momentum diffusivity

Description : Prandtl number is the ratio of (A) Mass diffusivity to thermal diffusivity (B) Momentum diffusivity to thermal diffusivity (C) Thermal diffusivity to mass diffusivity (D) Thermal diffusivity to momentum diffusivity

Last Answer : (B) Momentum diffusivity to thermal diffusivity

Dittus-Boelter equation cannot be used for molten metals mainly due to its very low (A) Prandtl number (B) Grashoff number (C) Thermal conductivity (D) Viscosity

Description : Dittus-Boelter equation cannot be used for molten metals mainly due to its very low (A) Prandtl number (B) Grashoff number (C) Thermal conductivity (D) Viscosity

Last Answer : (A) Prandtl number

Prandtl number is the ratio of (A) Momentum diffusivity to mass diffusivity (B) Momentum diffusivity to thermal diffusivity (C) Thermal diffusivity to mass diffusivity (D) Thermal diffusivity to momentum diffusivity

Description : Prandtl number is the ratio of (A) Momentum diffusivity to mass diffusivity (B) Momentum diffusivity to thermal diffusivity (C) Thermal diffusivity to mass diffusivity (D) Thermal diffusivity to momentum diffusivity

Last Answer : (B) Momentum diffusivity to thermal diffusivity

Prandtl number is the reciprocal of (A) Thermal diffusivity/Momentum diffusivity (B) Thermal diffusivity × Momentum (C) Thermal diffusivity × Mass diffusivity (D) Mass diffusivity × Momentum diffusivity

Description : Prandtl number is the reciprocal of (A) Thermal diffusivity/Momentum diffusivity (B) Thermal diffusivity × Momentum (C) Thermal diffusivity × Mass diffusivity (D) Mass diffusivity × Momentum diffusivity

Last Answer : (A) Thermal diffusivity/Momentum diffusivity

Direct conversion of thermal energy to electrical energy is facilitated by the (A) Fuel cells (B) Photo voltaic cell (C) Magneto hydrodynamic generator (D) None of these

Description : Direct conversion of thermal energy to electrical energy is facilitated by the (A) Fuel cells (B) Photo voltaic cell (C) Magneto hydrodynamic generator (D) None of these

Last Answer : (C) Magneto hydrodynamic generator

In catalytic cracking process, olefins crack __________ times faster than in thermal cracking process. (A) 100 (B) 200-300 (C) 1000-10000 (D) 10

Description : In catalytic cracking process, olefins crack __________ times faster than in thermal cracking process. (A) 100 (B) 200-300 (C) 1000-10000 (D) 10

Last Answer : (C) 1000-10000

Nuclear power generation capacity in India is (A) 3000 MW (B) 10000 MW (C) More than hydroelectric power generation capacity (D) More than thermal power generation capacity

Description : Nuclear power generation capacity in India is (A) 3000 MW (B) 10000 MW (C) More than hydroelectric power generation capacity (D) More than thermal power generation capacity

Last Answer : (A) 3000 MW

Archimedes principle states that  a. when a body is inversed in a fluid, the fluid exerts a downward force on the body whose magnitude is equal to the weight of the displaced fluid  b. when a body is inversed in a fluid, the fluid exerts a upward force on the body whose magnitude is equal to the weight of the displaced fluid.  c. when a body is inversed in a fluid, the fluid exerts a downward force on the body whose magnitude is greater than the weight of the displaced fluid.  d. when a body is inversed in a fluid, the fluid exerts a downward force on the body whose magnitude is lower than the weight of the displaced fluid.

Description : Archimedes principle states that  a. when a body is inversed in a fluid, the fluid exerts a downward force on the body whose magnitude is equal to the weight of the displaced fluid  b. ... fluid exerts a downward force on the body whose magnitude is lower than the weight of the displaced fluid.

Last Answer : when a body is inversed in a fluid, the fluid exerts a upward force on the body whose magnitude is equal to the weight of the displaced fluid.

One face of a furnace wall is at 1030°C and the other face is exposed to room temperature (30°C). If the thermal conductivity of furnace wall is 3 W. m-1. k-1 and the wall thickness is 0.3 m, the maximum heat loss (in W/m) is (A) 100 (B) 900 (C) 9000 (D) 10000

Description : One face of a furnace wall is at 1030°C and the other face is exposed to room temperature (30°C). If the thermal conductivity of furnace wall is 3 W. m-1. k-1 and the wall thickness is 0.3 m, the maximum heat loss (in W/m) is (A) 100 (B) 900 (C) 9000 (D) 10000

Last Answer : (D) 10000

Thermal efficiency of a Carnot engine can approach 100%, only when the temperature of the (A) Cold reservoir approaches zero (B) Hot reservoir approaches infinity (C) Either (A) or (B) (D) Neither (A) nor (B)

Description : Thermal efficiency of a Carnot engine can approach 100%, only when the temperature of the (A) Cold reservoir approaches zero (B) Hot reservoir approaches infinity (C) Either (A) or (B) (D) Neither (A) nor (B)

Last Answer : C) Either (A) or (B)

According to the second law of thermodynamics, energy tends to become more and more unavailable for conversion from: w) thermal to kinetic energy x) kinetic to thermal energy y) thermal to mechanical energy z) mechanical to thermal energy

Description : According to the second law of thermodynamics, energy tends to become more and more unavailable for conversion from: w) thermal to kinetic energy x) kinetic to thermal energy y) thermal to mechanical energy z) mechanical to thermal energy

Last Answer : ANSWER: Y -- THERMAL TO MECHANICAL ENERGY

When the ratio of the Grashoff number and to the square of Reynolds number is one, the dominant mechanism of heat transfer is: (A) Free convection (B) Entry length problem in laminar forced conduction (developing thermal boundary layer) (C) Mixed convection (both free and forced) (D) Forced convection

Description : When the ratio of the Grashoff number and to the square of Reynolds number is one, the dominant mechanism of heat transfer is: (A) Free convection (B) Entry length problem in laminar forced ... (developing thermal boundary layer) (C) Mixed convection (both free and forced) (D) Forced convection

Last Answer : (C) Mixed convection (both free and forced)

Gemfibrozil has the following features except: A. It lowers plasma LDL cholesterol to a greater extent than triglycerides B. It tends to raise plasma HDL-cholesterol level C. It is a first line drug for type III, type IV and type V hyperlipoproteinemia D. It reduces the incidence of myocardial infarctio

Description : Gemfibrozil has the following features except: A. It lowers plasma LDL cholesterol to a greater extent than triglycerides B. It tends to raise plasma HDL-cholesterol level C. It is a first ... type III, type IV and type V hyperlipoproteinemia D. It reduces the incidence of myocardial infarctio

Last Answer : A. It lowers plasma LDL cholesterol to a greater extent than triglycerides

Which one the following is a correct statement? (A) The vertical section of the soil extending into the parent material, is called profile(B) The layers of the soil parallel to the earth surface are called horizons (C) The transitional layer between two adjoining horizons is called boundary (D) All of these

Description : Which one the following is a correct statement? (A) The vertical section of the soil extending into the parent material, is called profile (B) The layers of the soil parallel to the earth ... horizons (C) The transitional layer between two adjoining horizons is called boundary (D) All of these

Last Answer : Answer: Option D

The term critical angle describes ∙ A. the point at which light is refracted ∙ B. the point at which light becomes invisible ∙ C. the point at which light has gone from the refractive mode to the reflective mode ∙ D. the point at which light has crossed the boundary layers from one index to another

Description : The term critical angle describes ∙ A. the point at which light is refracted ∙ B. the point at which light becomes invisible ∙ C. the point at which light has gone from the refractive mode ... reflective mode ∙ D. the point at which light has crossed the boundary layers from one index to another

Last Answer : C. the point at which light has gone from the refractive mode to the reflective mode ∙

The termcritical angle describes a. the point at which light is refracted b. the point at which light becomes invisible c. the point at which light has gone from the refractive mode to the reflective mode d. the point at which light has crossed the boundary layers from one index to another

Description : The termcritical angle describes a. the point at which light is refracted b. the point at which light becomes invisible c. the point at which light has gone from the refractive mode to the reflective mode d. the point at which light has crossed the boundary layers from one index to another

Last Answer : c. the point at which light has gone from the refractive mode to the reflective mode