Q. The thickness of thermal boundary layer is arbitrarily defined as the distance from the plate surface at which

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Q. The convection of energy reduces the outward conduction in the fluid so temperature gradient

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Q. The velocity profile of the hydrodynamic boundary layer is dependent upon

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Q. Which is true for two dimensional boundary layer?

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Q. The differential energy equation for flow past a flat plate is given by

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Q. The assumptions for thermal boundary layer are

(i) Steady compressible flow
(ii) Negligible body forces, viscous heating and conduction in the flow direction
(iii) Constant fluid properties evaluated at the film temperature

Identify the correct option

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Q. The relationship between the thermal and hydrodynamic boundary layer thickness is governed by the

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Q. A small thermo-couple is positioned in a thermal boundary layer near a flat plate past which water flows at 30 degree Celsius and 0.15 m/s. The plate is heated to a surface temperature of 50 degree Celsius and at the location of the probe, the thickness is 15 mm. The probe is well-represented by

t – t S/t INFINITY – t S = 1.5 (y/δ) – 0.5 (y/δ)³

Determine the heat transfer coefficient

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Q. Air at 25 degree Celsius approaches a 0.9 m long and 0.6 m wide flat plate with a velocity 4.5 m/s. Let the plate is heated to a surface temperature of 135 degree Celsius. Find local heat transfer coefficient from the leading edge at a distance of 0.5 m

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Q. A small thermo-couple is positioned in a thermal boundary layer near a flat plate past which water flows at 30 degree Celsius and 0.15 m/s. The plate is heated to a surface temperature of 50 degree Celsius and at the location of the probe, the thickness of thermal boundary layer is 15 mm. If the temperature profile as measured by the probe is well-represented by

t – t S/t INFINITY – t S = 1.5 (y/δ t) – 0.5 (y/δ t)³

Determine the heat flux from plate to water

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Q. Atmospheric air at 30 degree Celsius temperature and free stream velocity of 2.5 m/s flows along the length of a flat plate maintained at a uniform surface temperature of 90 degree Celsius. Let length = 100 cm, width = 50 cm and thickness = 2.5 cm. Thermal conductivity of the plate material is 25 W/m K, find heat lost by the plate

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Q. Ambient air at 20 degree Celsius flows past a flat plate with a sharp leading edge at 3 m/s. The plate is heated uniformly throughout its entire length and is maintained at a surface temperature of 40 degree Celsius. Calculate the distance from the leading edge at which the flow in the boundary layer changes from laminar to turbulent conditions. Assume that transition occurs at a critical Reynolds number of 500000

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Q. Ambient air at 20 degree Celsius flows past a flat plate with a sharp leading edge at 3 m/s. The plate is heated uniformly throughout its entire length and is maintained at a surface temperature of 40 degree Celsius. Calculate the thickness of the hydrodynamic boundary layer. Assume that transition occurs at a critical Reynolds number of 500000

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Q. Ambient air at 20 degree Celsius flows past a flat plate with a sharp leading edge at 3 m/s. The plate is heated uniformly throughout its entire length and is maintained at a surface temperature of 40 degree Celsius. Calculate the thickness of the thermal boundary layer. Assume that transition occurs at a critical Reynolds number of 500000

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Q. Ambient air at 20 degree Celsius flows past a flat plate with a sharp leading edge at 3 m/s. The plate is heated uniformly throughout its entire length and is maintained at a surface temperature of 40 degree Celsius. Calculate the local convective heat transfer coefficient. Assume that transition occurs at a critical Reynolds number of 500000

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Q. Temperature and velocity profiles are identical when the dimensionless Prandtl number is

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Q. Reynolds analogy is given by

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Q. The average drag coefficient for turbulent boundary layer flow past a thin plate is given by

Cf = 0.455/ (log10 Rel)^2.58

Where R el is the Reynolds number based on plate length. A plate 50 cm wide and 5 m long is kept parallel to the flow of water with free stream velocity 3 m/s. Calculate the drag force on both sides of the plate. For water, kinematic viscosity = 0.01 stokes

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Q. During test-run, air flows at 215 m/s velocity and 25 degree Celsius temperature past a smooth thin model airfoil which can be idealized as a flat plate. If the chord length of the airfoil is 15 cm, find drag per unit width. The relevant physical properties of air are

p = 1.82 kg/m³
v = 15.53 * 10¯⁶ m²/s

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Q. A flat plate was positioned at zero incidence in a uniform flow stream of air. Assuming boundary layer to be turbulent over the entire plate, workout the ratio of skin-friction forces on the front and rear half part of the plate

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