Fluid Mechanics
8th Edition
ISBN: 9780073398273
Author: Frank M. White
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 7, Problem 7.2P
A gas at 20°C and 1 atm flows at 6 ft/s past a thin flat plate. At x = 3 ft. the boundary layer thickness is 0.052 ft. Assuming laminar flow, which of the gases in Table A.4 is this likely to be?
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We are testing a flat plate of length L = 1.125 m and width W = 0.225 m in a stream of air flowing with a velocity of 20 m/s. In test case 1, the air is flowing parallel to L and in test case 2 air is flowing parallel to W. Find:
What portion of the boundary layer flow is laminar in each case?
What is the highest laminar boundary layer thickness in each case?
Assuming the flow is entirely turbulent over the plate, calculate the drag force in both test cases
Take air density as 1.2 kg/m3 and its viscosity as μ=18×10−6μ=18×10−6 N.s/m2.
A gas at 20°C and 1 atm flow at 6 ft/s past a thin flat plate.At x = 3 ft, the boundary layer thickness is 0.052 ft.Assuming laminar flow, which of the gases in Table A.4 isthis likely to be?
An ideal gas, at 20°C and 1 atm, flows at 12 m/s past a thinflat plate. At a position 60 cm downstream of the leadingedge, the boundary layer thickness is 5 mm. Which of the13 gases in Table A.4 is this likely to be?
Chapter 7 Solutions
Fluid Mechanics
Ch. 7 - Prob. 7.1PCh. 7 - A gas at 20°C and 1 atm flows at 6 ft/s past a...Ch. 7 - Prob. 7.3PCh. 7 - Prob. 7.4PCh. 7 - SAE 30 oil at 20°C flows at 1.8 ft3/s from a...Ch. 7 - Prob. 7.6PCh. 7 - P7.7 Air at 20°C and 1 atm enters a 40-cm-square...Ch. 7 - P7.8 Air, p = 1.2 kg/m3 and E-5 kg/(m .s), flows...Ch. 7 - P7.9 Repeat the flat-plate momentum analysis of...Ch. 7 - Repeat Prob. P7.9, using a trigonometric profile...
Ch. 7 - Prob. 7.11PCh. 7 - Prob. 7.12PCh. 7 - Prob. 7.13PCh. 7 - Prob. 7.14PCh. 7 - Prob. 7.15PCh. 7 - A thin flat plate 55 by 110 cm is immersed in a...Ch. 7 - Consider laminar flow past a sharp flat plate of...Ch. 7 - Air at 20°C and 1 atm flows at 5 m/s past a flat...Ch. 7 - Prob. 7.19PCh. 7 - Air at 20°C and I atm flows at 20 m/s past the...Ch. 7 - Prob. 7.21PCh. 7 - Prob. 7.22PCh. 7 - Prob. 7.23PCh. 7 - Prob. 7.24PCh. 7 - Prob. 7.25PCh. 7 - P7.26 Consider laminar boundary layer flow past...Ch. 7 - Prob. 7.27PCh. 7 - Prob. 7.28PCh. 7 - Prob. 7.29PCh. 7 - Prob. 7.30PCh. 7 - Prob. 7.31PCh. 7 - Prob. 7.32PCh. 7 - Prob. 7.33PCh. 7 - Prob. 7.34PCh. 7 - Prob. 7.35PCh. 7 - Prob. 7.36PCh. 7 - Prob. 7.37PCh. 7 - Prob. 7.38PCh. 7 - P7.39 A hydrofoil 50 cm long and 4 m wide moves...Ch. 7 - Prob. 7.40PCh. 7 - Prob. 7.41PCh. 7 - Prob. 7.42PCh. 7 - Prob. 7.43PCh. 7 - Prob. 7.44PCh. 7 - P7.45 A thin sheet of fiberboard weighs 90 N and...Ch. 7 - Prob. 7.46PCh. 7 - Prob. 7.47PCh. 7 - Prob. 7.48PCh. 7 - Based strictly on your understanding of flat-plate...Ch. 7 - Prob. 7.50PCh. 7 - Prob. 7.51PCh. 7 - Prob. 7.52PCh. 7 - Prob. 7.53PCh. 7 - *P7.54 If a missile takes off vertically from sea...Ch. 7 - Prob. 7.55PCh. 7 - Prob. 7.56PCh. 7 - Prob. 7.57PCh. 7 - Prob. 7.58PCh. 7 - Prob. 7.59PCh. 7 - Prob. 7.60PCh. 7 - Prob. 7.61PCh. 7 - A sea-level smokestack is 52 m high and has a...Ch. 7 - For those who think electric cars are sissy, Keio...Ch. 7 - Prob. 7.64PCh. 7 - Prob. 7.65PCh. 7 - Prob. 7.66PCh. 7 - The Toyota Prius has a drag coefficient of 0.25, a...Ch. 7 - Prob. 7.68PCh. 7 - Prob. 7.69PCh. 7 - P7.70 The Army’s new ATPS personnel parachute is...Ch. 7 - Prob. 7.71PCh. 7 - Prob. 7.72PCh. 7 - Prob. 7.73PCh. 7 - Prob. 7.74PCh. 7 - Prob. 7.75PCh. 7 - P7.76 The movie The World’s Fastest Indian tells...Ch. 7 - Prob. 7.77PCh. 7 - Prob. 7.78PCh. 7 - Prob. 7.79PCh. 7 - Prob. 7.80PCh. 7 - Prob. 7.81PCh. 7 - Prob. 7.82PCh. 7 - Prob. 7.83PCh. 7 - P7.84 A Ping-Pong ball weighs 2.6 g and has a...Ch. 7 - Prob. 7.85PCh. 7 - Prob. 7.86PCh. 7 - P7.87 A tractor-trailer truck has a drag area CA =...Ch. 7 - P7.88 A pickup truck has a clean drag area CDA of...Ch. 7 - Prob. 7.89PCh. 7 - Prob. 7.90PCh. 7 - Prob. 7.91PCh. 7 - Prob. 7.92PCh. 7 - A hot-film probe is mounted on a cone-and-rod...Ch. 7 - Baseball drag data from the University of Texas...Ch. 7 - Prob. 7.95PCh. 7 - Prob. 7.96PCh. 7 - Prob. 7.97PCh. 7 - A buoyant ball of specific gravity SG 1 dropped...Ch. 7 - Prob. 7.99PCh. 7 - Prob. 7.100PCh. 7 - Prob. 7.101PCh. 7 - Prob. 7.102PCh. 7 - Prob. 7.103PCh. 7 - Prob. 7.104PCh. 7 - Prob. 7.105PCh. 7 - Prob. 7.106PCh. 7 - Prob. 7.107PCh. 7 - Prob. 7.108PCh. 7 - Prob. 7.109PCh. 7 - Prob. 7.110PCh. 7 - Prob. 7.111PCh. 7 - Prob. 7.112PCh. 7 - Prob. 7.113PCh. 7 - Prob. 7.114PCh. 7 - Prob. 7.115PCh. 7 - Prob. 7.116PCh. 7 - Prob. 7.117PCh. 7 - Suppose that the airplane of Prob. P7.116 is...Ch. 7 - Prob. 7.119PCh. 7 - Prob. 7.120PCh. 7 - Prob. 7.121PCh. 7 - Prob. 7.122PCh. 7 - Prob. 7.123PCh. 7 - Prob. 7.124PCh. 7 - Prob. 7.125PCh. 7 - Prob. 7.126PCh. 7 - Prob. 7.127PCh. 7 - Prob. 7.1WPCh. 7 - Prob. 7.2WPCh. 7 - Prob. 7.3WPCh. 7 - Prob. 7.4WPCh. 7 - Prob. 7.5WPCh. 7 - Prob. 7.6WPCh. 7 - Prob. 7.7WPCh. 7 - Prob. 7.8WPCh. 7 - Prob. 7.9WPCh. 7 - How does the concept of drafting, in automobile...Ch. 7 - Prob. 7.11WPCh. 7 - Prob. 7.12WPCh. 7 - Prob. 7.1FEEPCh. 7 - Prob. 7.2FEEPCh. 7 - Prob. 7.3FEEPCh. 7 - Prob. 7.4FEEPCh. 7 - Prob. 7.5FEEPCh. 7 - Prob. 7.6FEEPCh. 7 - Prob. 7.7FEEPCh. 7 - Prob. 7.8FEEPCh. 7 - Prob. 7.9FEEPCh. 7 - Prob. 7.10FEEPCh. 7 - Prob. 7.1CPCh. 7 - Prob. 7.2CPCh. 7 - Prob. 7.3CPCh. 7 - Prob. 7.4CPCh. 7 - Prob. 7.5CPCh. 7 - It is desired to design a cup anemometer for wind...
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- Air at 1000C flows at an inlet velocity of 2 m/s between two parallel flat plates spaced 1 cm apart. Estimate the distance from the entrance to the point where the boundary layers meet.arrow_forward2. Air at 40 °C moves over a long flat plate with a uniform free stream velocity of U = 900 m/s. Assume the boundary layer formed above the surface of the plate starts at the tip of the leading edge and the velocity profile inside the boundary layer has power-law form as Re, <107 8 10' < Re, <10* 7 - (). for u Sxarrow_forwardPu Wings at supersonic flows can be modeled as a flat plate that have constant pressure distributions across their chord. Ignoring any viscous effects determine the drag force of the wing section. Round to the full N/m and make sure you use the standard sign convention (i.e. right hand rule). Use the following data chord = 1.5 m epsilon = 5 degree angle of attack = 20.0 alpha upper surface pressure = 60,000 Pa lower surface pressure = 150,000 Paarrow_forwardQuestionNo.3 An approximated velocity profile for a laminar boundary layer is given as u(y) × Usin| 28 where U is the stream velocity far from the wall and 8 is the boundary layer thickness, as shown in Fig 2. If the fluid is helium (µ = 1.94 × 10-5N.s/m²) at 20°C and 1 atm, and if U = 10.8 m/s and ô= 3 cm, %3D use the formula to (a) Estimate the wall shear stress Tw in N/m2, and (b) Find the position in the boundary layer where t is one-half of Tw 2/2 U y = 8 u(y) Figure 2arrow_forward6- A uniform free stream of air at 0.8 m/s flows over a flat plate (4 m long x 1 m wide). Assuming the boundary layer to be laminar on the plate and the velocity profile is: и Find the ratio of the drag force on the front half portion to the drag %3D U force on the rear half portion of the plate. (p = 1.2 kg/m ; v= 1.51×10* m³/s) [2.42]arrow_forwardAir at 15°C forms a boundary layer near a solid wall. The velocity distribution in the boundary layer is given by: u/U = 1- exp (-2y/8), where U 35 m/sec. and 8 = 0.8 cm. Find the shear stress at wall (y 0).arrow_forward6- A uniform free stream of air at 0.8 m/s flows over a flat plate (4 m long x 1 m wide). Assuming the boundary layer to be laminar on the plate and the velocity profile is: Find the ratio of the drag force on the front half portion to the drag U. 2 force on the rear half portion of the plate. (p = 1.2 kg/m; v = 1.51x10 m²/s) [2.42]arrow_forwardAir at 7 kN/m^2 and 35°C flows over a flat square plate sideways at a velocity of 7.5 m/s, side measure is 30 cm. The plate is maintained at a temperature of 65 °C. Calculate the heat lost by the board.Note: The properties μ, k, cp and Pr for air at 1 atm are valid for the pressure presented in this problem.arrow_forwardQ5. A deep pool of oil having kinematic viscosity 3.45x10 m²/s is resting over a flat plate. The plate is suddenly set into motion with velocity 5 cm/s at time t-0. What will be the boundary layer thickness after 10s when the plate was set in motion?arrow_forward(b) A smooth thin plate 10 m long and 1 m wide is placed in an air stream at 3 m/s with its length parallel with the flow. Determine the total drag force acting on the plate if the air temperature is 30°C. (c) Based on question Q4(b), determine the total drag force acting on the thin plate if the length of the plate is 3 m long and the air stream velocity is 1 m/s.arrow_forwardAir at T = 25 C° and p = 1 atm flows past a long flat plate, at the end of which is placed a narrow scoop, as shown in the figure below. (a) Determine if the boundary layer is laminar or turbulent at the position of the scoop assuming Re,trans = 5 x 10°; (b) estimate the height h of the scoop if it is to extract 4 kg/s per meter of width b into the paper. (c) Find the drag on the plate per meter of width, D/b up to the inlet of the scoop.arrow_forward3. Use scale analysis to find an expression for S/L and Nu, for flow over a flat plate with both boundary layers of equal thickness (8=ST)arrow_forwardarrow_back_iosSEE MORE QUESTIONSarrow_forward_ios
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