Choose false statement about boundary layer 2 po O Boundary layer happens due to zero momentum at the solid stationary boundary After some initial length, the thickness of the boundary layer gets constant value in pipe flow O Turbulent boundary layer has more thickness than the laminar one O All of the above O Thermal boundary layer is not always thicker than velocity boundary layer O None of the above

Choose false statement about boundary layer 2 po O Boundary layer happens due to zero momentum at the solid stationary boundary After some initial length, the thickness of the boundary layer gets constant value in pipe flow O Turbulent boundary layer has more thickness than the laminar one O All of the above O Thermal boundary layer is not always thicker than velocity boundary layer O None of the above

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter5: Analysis Of Convection Heat Transfer

Section: Chapter Questions

Problem 5.31P

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2.0 m 7: 10.0 m = 2²-²² Us B 10.0 m Figure Q1-2 Question 2 Air flow at a constant speed (Us = 10 m/s) is forming a two-dimensional incompressible laminar boundary layer along a flat plate The velocity profile inside the boundary layer is given by: 2.0 m (Equation 1) At x = 1.00 m, the boundary layer thickness is given as 6.6094 mm. At this location: a) Determine the shear stress at the wall, at y = 3 mm and y = 10 mm. b) Calculate the boundary layer displacement thickness. c) Calculate the mass flow rate through the boundary layer per unit width. d) Calculate the mass flow rate per unit width of an ideal flow going through the same height as the boundary layer thickness. e) Through calculation relate the difference between the mass flow rates in parts (c) and (d) to the local boundary layer displacement thickness. In not more than 60 word justify your answer. Use sketch(s) to illustrate your justification. f) Does the assumed velocity profile satisfy the pressure boundary condition? In…
A boundary layer is a region of flow next to the surface of a body where Bernoulli's equation is valid the flow is always laminar the flow is always turbulent the flow is irrotational viscous effects are significant
Introduction to heat convection Solved problems HW-10- 1- Determine the velocity distribution in the velocity boundary layer assuming second degree polynomial: u =C, +C,y+C,y? Answer: The boundary conditions are: du .. u = 0 at y = 0; u = u, ; at y = 6; = 0 at y = 8 dy 2 y This gives: يجب حفظ الشروط الحدية اذا كان الامتحان حضوري 2- Determine the velocity distribution in the velocity boundary layer assuming third degree polynomial: u = C, +C,y+C,y' +C,y' Answer: The boundary conditions are: .. u = 0 at y = 0 = 0 dy? at y = 0 du = 0 u = u, at y = 8 at y = 8 dy 3 y 1y This gives: 28 28 يجب حفظ الشروط الحدية اذا كان الامتحان حضوري 3- Determine the velocity distribution in the velocity boundary layer assuming fourth degree polynomial: 2 u = a, +a, y+a,y +a,y' +a,y Answer: The boundary conditions are: . u = 0 = 0 dy? at y = 0 at y = 0 du = 0 dy d'u at y = 6 ; dy? u = u, at y = 6 at y = 6 4. This gives: = 2 يجب حفظ الشروط الحدية اذا كان الامتحان حضوري 4- For flow over a slightly curved…
1. In the figure shown below, choose whether the statement is true or false (Please justify your answer) (a) At a give x-location, if Re were to increase, the boundary layer thickness would decrease. (b) As upstream velocity decreases, so does the boundary layer thickness (c) As the kinematic viscosity increases, so does the boundary layer thickness (d) As the fluid density decreases, so does the boundary layer thickness (e) As the x-location increases, so does the boundary layer thickness
(b) In two dimensional boundary layer, shear stress was changed linearly from the solid surface toward y-axis until it reach the value of zero at y = ở. Based on Table 2 and setting given to you; (i) Derive the equation of displacement thickness and momentum thickness using Von Karman Approximation Method ; and (ii) Determine the accuracy of this method in determining the value of displacement thickness and momentum thickness. C5 Table 2: Equation of Velocity Profile Setting Equation wU = 2y/8 - (y/S² 1
Air flow at a constant speed (Us = 10 m/s) is forming a two-dimensional incompressible laminar boundary layer along a flat plate The velocity profile inside the boundary layer is given by: =2-² A wind tunnel designer plans to build a two dimensional test section for a low speed wind tunnel. The design specification requires that in the test section the free stream flow must be equal to the air velocity at the entrance of the test section. (Figure Q2). U 30 m/s h₁ = 2²-² x,-0.0 Top wall Bottom wall -300 mm X-300 mm Figure Q2 Assuming the same velocity profile as in equation 1, and by using the momentum integral equation determine how much the bottom and top walls should be displaced at point 2 (x₂ = 300 mm) in order to achieve the design requirement as was stated above. In not more than 30-40 words justify your solution. Equation 1:
An air whose cross-sections are visible in the figure on the side Channel 40 cm diameter and 60 cm tall test section references The air temperature is 200oC. At the entrance of the Test section A uniform airspeed of 2 m/s was measured.a) the number of Reynolds at the end of the test section (Rex)calculate.b) limit layer thickness at the end of the test sectioncalculate.c) air velocity test on centerlinewhat percentage increases by the end of the section,calculate.d) local surface friction at the end of the test sectioncalculate the coefficient. v = 1,516 . 10-5 m2/s.
(b) In two-dimensional boundary layer, shear stress was changed linearly from the solid surface toward y-axis until it reach the value of zero at y = 8. Based on Table 2 and setting given to you; (i) Derive the equation of displacement thickness and momentum thickness using Von Karman Approximation Method ; and (ii) Determine the accuracy of this method in determining the value of displacement thickness and momentum thickness. Table 2: Equation of Velocity Profile Equation u/U = 3(y/S)/2 – (y/8)³/2
(b) In two-dimensional boundary layer, shear stress was changed linearly from the solid surface toward y-axis until it reaches the value of zero at y = 8. Based on Table 2 and setting given to you; (i) Derive the equation of displacement thickness and momentum thickness using Von Karman Approximation Method; and (ii) Determine the accuracy of this method in determining the value of displacement thickness and momentum thickness. Table 2: Equation of Velocity Profile Equation u/U = 3(y/8)/2 – (y/8)³/2 Setting 2
(b) In two dimensional boundary layer, shear stress was changed linearly from the solid surface toward y-axis until it reach the value of zero at y = 6. Based on Table 2 and setting given to you; () Derive the equation of displacement thickness and momentum thickness using Von Karman Approximation Method ; and (ii) Determine the accuracy of this method in determining the value of displacement thickness and momentum thickness. Table 2 : Equation of Velocity Profile Setting Equation wU = 3(y/8)/2 – (y/8j?/2
between two concentric spherical sheets there is air. The inner spherical sheet has a radius of 10 cm and is filled with ice at 0 ° C, the outer spherical sheet has a radius of 10.05 cm and is at a temperature of 15 ° C. What amount of heat will be transmitted from one sheet to another by conductivity ends in 1/4 hour ?. Considering that the air is pressurized, it is considered to be 15 N / m ^ 2 and at a temperature of 2 ° C. The diameter of the air molecules is taken equal to 3 x 10 ^ -10 m. the molar mass of air is taken equal to 29 g / mol; Boltzman's constant k = 1.38 x 10 ^ -23 J / K
This exercise is part of a series of problems aimed at modeling a situation by progressively refining our model to take into account more and more parameters. This progressive approach is very close to whatwhat do professional scientists do! contextWe want to lower a suspended load in a controlled way, so that it hits the ground with a speed whose modulus is not too great. To slow down the descent, we added a resort behind the mass (A), Lasuspended load (B) is connected by a rope passing through a pulley to another mass (A), which slides on a horizontal surface with friction.InformationThe masses of loads A and B are known.The mass of the rope itself is negligible (very small compared to the loads).The pulley has negligible mass and can rotate without friction.Load B is initially stationary and is at a known height h.The surface on which mass A is placed is horizontal.There is friction under mass A: the kinetic friction coefficient u, is known.The rope attached to mass A is perfectly…