Fluid Mechanics
8th Edition
ISBN: 9780073398273
Author: Frank M. White
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 5, Problem 5.2P
A prototype automobile is designed for cold weather in Denver, CO (−10°C, 83 kPa). Its drag force is to be tested on a one-seventh-scale model in a wind tunnel at 150 mi/h, 20°C, and 1 atm. If the model and proto type are to satisfy dynamic similarity, what prototype velocity, in mi/h, needs to be matched? Comment on your result.
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2
A prototype car is designed for cold weather operation in Denver (-10°C, 83 kPa,
altitude 1600m, µ = 1.741 × 10-5 Pas). It's drag force is to be tested in a 1:7 model in a
wind tunnel at 150 mph under standard sea level conditions.
If the model and prototype satisfy dynamic similarity what prototype velocity, in mph, is
matched? Is this a reasonable test?
1 mile = 1609 m
HINT: p = pRT
(b) A wind-tunnel experiment is performed on a small 1:5 linear-scale model of a car, in order
to assess the drag force F on a new full-size car design. A dimensionless "drag coefficient"
Ca is defined by
C, =-
pu'A
where A is the maximum cross-sectional area of the car in the flow. With the model car, a
force of 3 N was recorded at a flow velocity u of 6 m s. Assuming that flow conditions
are comparable (i.e., at the same Reynolds number), calculate the expected drag force for
the full-sized car when the flow velocity past it is 31 m s (equivalent to 70 miles per
hour). [The density of air p= 1.2 kg m.]
Q1: The drag on a 2m-diameter satellite dish due to an 80 km/hr wind is to be determined
through a water tunnel test using a geometrically similar 0.25m-diameter model dish.
(a) At what water speed should the model test be run?
(b) With all similarity conditions satisfied, the measured drag on the model was determined to be
200 N. What is the predicted drag on the prototype dish?
(c) What is the Mach number, Ma = u/a where a is the speed of sound, for the prototype air flow
and the one in the water tunnel?
PS: The kinematic viscosity of air is 1.56 x10-5 m²/s.-The kinematic viscosity of water is 1.0 x10-
6 m²/s. The speed of sound is 340 m/s in air and 1500 m/s in water.
Chapter 5 Solutions
Fluid Mechanics
Ch. 5 - Prob. 5.1PCh. 5 - A prototype automobile is designed for cold...Ch. 5 - P5.3 The transfer of energy by viscous dissipation...Ch. 5 - When tested in water at 20°C flowing at 2 m/s, an...Ch. 5 - P5.5 An automobile has a characteristic length and...Ch. 5 - P5.6 The disk-gap-band parachute in the...Ch. 5 - Prob. 5.7PCh. 5 - Prob. 5.8PCh. 5 - The Richardson number, Ri, which correlates the...Ch. 5 - Prob. 5.10P
Ch. 5 - Prob. 5.11PCh. 5 - The Stokes number, St, used in particle dynamics...Ch. 5 - Prob. 5.13PCh. 5 - Flow in a pipe is often measured with an orifice...Ch. 5 - The wall shear stress T in a boundary layer is...Ch. 5 - P5.16 Convection heat transfer data are often...Ch. 5 - If you disturb a tank of length L and water depth...Ch. 5 - Prob. 5.18PCh. 5 - Prob. 5.19PCh. 5 - Prob. 5.20PCh. 5 - Prob. 5.21PCh. 5 - As will be discussed in Chap. 11, the power P...Ch. 5 - The period T of vibration of a beam is a function...Ch. 5 - Prob. 5.24PCh. 5 - The thrust F of a propeller is generally thought...Ch. 5 - A pendulum has an oscillation period T which is...Ch. 5 - Prob. 5.27PCh. 5 - Prob. 5.28PCh. 5 - P5.29 When fluid in a pipe is accelerated linearly...Ch. 5 - Prob. 5.30PCh. 5 - P5.31 The pressure drop per unit length in...Ch. 5 - A weir is an obstruction in a channel flow that...Ch. 5 - Prob. 5.33PCh. 5 - Prob. 5.34PCh. 5 - Prob. 5.35PCh. 5 - Prob. 5.36PCh. 5 - Prob. 5.37PCh. 5 - Prob. 5.38PCh. 5 - Prob. 5.39PCh. 5 - Prob. 5.40PCh. 5 - A certain axial flow turbine has an output torque...Ch. 5 - When disturbed, a floating buoy will bob up and...Ch. 5 - Prob. 5.43PCh. 5 - Prob. 5.44PCh. 5 - P5.45 A model differential equation, for chemical...Ch. 5 - P5.46 If a vertical wall at temperature Tw is...Ch. 5 - The differential equation for small-amplitude...Ch. 5 - Prob. 5.48PCh. 5 - P5.48 A smooth steel (SG = 7.86) sphere is...Ch. 5 - Prob. 5.50PCh. 5 - Prob. 5.51PCh. 5 - Prob. 5.52PCh. 5 - Prob. 5.53PCh. 5 - Prob. 5.54PCh. 5 - Prob. 5.55PCh. 5 - P5.56 Flow past a long cylinder of square...Ch. 5 - Prob. 5.57PCh. 5 - Prob. 5.58PCh. 5 - Prob. 5.59PCh. 5 - Prob. 5.60PCh. 5 - Prob. 5.61PCh. 5 - Prob. 5.62PCh. 5 - The Keystone Pipeline in the Chapter 6 opener...Ch. 5 - Prob. 5.64PCh. 5 - Prob. 5.65PCh. 5 - Prob. 5.66PCh. 5 - Prob. 5.67PCh. 5 - For the rotating-cylinder function of Prob. P5.20,...Ch. 5 - Prob. 5.69PCh. 5 - Prob. 5.70PCh. 5 - The pressure drop in a venturi meter (Fig. P3.128)...Ch. 5 - Prob. 5.72PCh. 5 - Prob. 5.73PCh. 5 - Prob. 5.74PCh. 5 - Prob. 5.75PCh. 5 - Prob. 5.76PCh. 5 - Prob. 5.77PCh. 5 - Prob. 5.78PCh. 5 - Prob. 5.79PCh. 5 - Prob. 5.80PCh. 5 - Prob. 5.81PCh. 5 - A one-fiftieth-scale model of a military airplane...Ch. 5 - Prob. 5.83PCh. 5 - Prob. 5.84PCh. 5 - *P5.85 As shown in Example 5.3, pump performance...Ch. 5 - Prob. 5.86PCh. 5 - Prob. 5.87PCh. 5 - Prob. 5.88PCh. 5 - P5.89 Wall friction Tw, for turbulent flow at...Ch. 5 - Prob. 5.90PCh. 5 - Prob. 5.91PCh. 5 - Prob. 5.1WPCh. 5 - Prob. 5.2WPCh. 5 - Prob. 5.3WPCh. 5 - Prob. 5.4WPCh. 5 - Prob. 5.5WPCh. 5 - Prob. 5.6WPCh. 5 - Prob. 5.7WPCh. 5 - Prob. 5.8WPCh. 5 - Prob. 5.9WPCh. 5 - Prob. 5.10WPCh. 5 - Given the parameters U,L,g,, that affect a certain...Ch. 5 - Prob. 5.2FEEPCh. 5 - Prob. 5.3FEEPCh. 5 - Prob. 5.4FEEPCh. 5 - Prob. 5.5FEEPCh. 5 - Prob. 5.6FEEPCh. 5 - Prob. 5.7FEEPCh. 5 - Prob. 5.8FEEPCh. 5 - In supersonic wind tunnel testing, if different...Ch. 5 - Prob. 5.10FEEPCh. 5 - Prob. 5.11FEEPCh. 5 - Prob. 5.12FEEPCh. 5 - Prob. 5.1CPCh. 5 - Prob. 5.2CPCh. 5 - Prob. 5.3CPCh. 5 - Prob. 5.4CPCh. 5 - Does an automobile radio antenna vibrate in...Ch. 5 - Prob. 5.1DPCh. 5 - Prob. 5.2DP
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