Fluid Mechanics Fundamentals And Applications
3rd Edition
ISBN: 9780073380322
Author: Yunus Cengel, John Cimbala
Publisher: MCGRAW-HILL HIGHER EDUCATION
expand_more
expand_more
format_list_bulleted
Videos
Textbook Question
Chapter 7, Problem 44P
Consider the common situation in which a researcher is trying to match the Reynolds number of a large prototype vehicle with that of a small-scale model in a wind tunnel. Is it better for the air in time wind tunnel to be cold or hot? Why? Support your argument by comparing wind tunnel air at 10 °C and at 45°C, all else being equal.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
The drag force on a submarine, which is moving on the surface, is to be determined by a test on
a model which is scaled down to one-twentieth of the prototype. The test is to be carried in a
towing tank, where the model submarine is moved along a channel of liquid. The density and the
kinematic viscosity of the seawater are 1010 kg/m³ and 1.3x10-6 m 2/s, respectively. The speed
of the prototype is 2.6 m/s. Assume that F = f(V, L. g. p.), using pi-theorem and similarity
principle to:
a) Determine the speed at which the model should be moved in the towing tank.
b) Determine the kinematic viscosity of the liquid that should be used in the towing tank.
A 1:7 scale model simulates the operation of a large turbine that is to generate200 kW with a flow rate of 1.5 m3/s. What flow rate should be used in the model, andwhat power output is expected?(a) Water at the same temperature is used in both model and prototype.(b) The model water is at 25°C and the prototype water is at 10°C.
An engineer is to design a human powered submarine for a design competition. The overall length of the prototype submarine is 2.24 m and its engineer designers hope that it can travel fully submerged through water at 0.560 m/s. The water is freshwater (a lake) at 7-15°C (p=999.1 kg/m3 and u= 1.138 ×103 kg/m-st. The design team builds a one-eighth scale model to test in their university's wind tunnel. The air in the wind tunnel is at 25°C (p= 1.180 kg/m3 and u = 1.849 ×10-5 kg/m-s) and at one standard atmosphere pressure. At what air speed do they need to run the wind tunnel in order to achieve similarity?
Chapter 7 Solutions
Fluid Mechanics Fundamentals And Applications
Ch. 7 - List the seven primary dimensions. What is...Ch. 7 - What is the difference between a dimension and a...Ch. 7 - Write the primary dimensions of the universal...Ch. 7 - Write the primary dimensions of each of the...Ch. 7 - Prob. 5PCh. 7 - Prob. 6PCh. 7 - On a periodic chart of the elements, molar mass...Ch. 7 - Prob. 8PCh. 7 - Prob. 9PCh. 7 - The moment of force(M)is formed by the cross...
Ch. 7 - Prob. 11PCh. 7 - You are probably familiar with Ohm law for...Ch. 7 - Write the primary dimensions of each of the...Ch. 7 - Prob. 14PCh. 7 - Prob. 15PCh. 7 - Thermal conductivity k is a measure of the ability...Ch. 7 - Write the primary dimensions of each of the...Ch. 7 - Prob. 18PCh. 7 - Prob. 19EPCh. 7 - Explain the law of dimensional homogeneity in...Ch. 7 - In Chap. 4, we defined the material acceleration,...Ch. 7 - Newton's second law is the foundation for the...Ch. 7 - Prob. 23PCh. 7 - Prob. 24PCh. 7 - An important application of fluid mechanics is the...Ch. 7 - Prob. 26PCh. 7 - Prob. 27PCh. 7 - What is the primary reason for nondimensionalizing...Ch. 7 - Prob. 29PCh. 7 - In an oscillating compressible flow field the...Ch. 7 - In Chap. 9, we define the stream function for...Ch. 7 - In an oscillating incompressible flow field the...Ch. 7 - Prob. 33PCh. 7 - Consider ventilation of a well-mixed room as in...Ch. 7 - List the three primary purposes of dimensional...Ch. 7 - List and describe the three necessary conditions...Ch. 7 - A student team is to design a human-powered...Ch. 7 - Repeat Prob. 7-34 with all the same conditions...Ch. 7 - This is a follow-tip to Prob. 7-34. The students...Ch. 7 - A lightweight parachute is being designed for...Ch. 7 - Prob. 41PCh. 7 - The aerodynamic drag of a new sports car is lo be...Ch. 7 - This is a follow-tip to Prob. 7-37E. The...Ch. 7 - Consider the common situation in which a...Ch. 7 - Some students want to visualize flow over a...Ch. 7 - Prob. 46PCh. 7 - Prob. 47PCh. 7 - Prob. 48PCh. 7 - Prob. 49PCh. 7 - Prob. 50PCh. 7 - A stirrer is used to mix chemicals in a large tank...Ch. 7 - Prob. 52PCh. 7 - Albert Einstein is pondering how to write his...Ch. 7 - The Richardson number is defined as Ri=L5gV2...Ch. 7 - Consider filly developed Couette flow-flow between...Ch. 7 - Consider developing Couette flow-the same flow as...Ch. 7 - The speed of sound c in an ideal gas is known to...Ch. 7 - Repeat Prob. 7-54, except let the speed of sound c...Ch. 7 - Repeat Prob. 7-54, except let the speed of sound c...Ch. 7 - Prob. 60PCh. 7 - When small aerosol particles or microorganisms...Ch. 7 - Prob. 62PCh. 7 - Prob. 63PCh. 7 - Prob. 64PCh. 7 - An incompressible fluid of density and viscosity ...Ch. 7 - Prob. 66PCh. 7 - One of the first things you learn in physics class...Ch. 7 - Prob. 68PCh. 7 - Bill is working on an electrical circuit problem....Ch. 7 - A boundary layer is a thin region (usually along a...Ch. 7 - A liquid of density and viscosity is pumped at...Ch. 7 - A propeller of diameter D rotates at angular...Ch. 7 - Repeat Prob. 7-68 for the case an which the...Ch. 7 - In the study of turbulent flow, turbulent viscous...Ch. 7 - Prob. 75PCh. 7 - Consider a liquid in a cylindrical container in...Ch. 7 - Prob. 77PCh. 7 - Prob. 78CPCh. 7 - Prob. 79CPCh. 7 - Prob. 80CPCh. 7 - Define wind tunnel blockage. What is the rule of...Ch. 7 - Prob. 82CPCh. 7 - In the model truck example discussed in Section...Ch. 7 - A small wind tunnel in a university's...Ch. 7 - Prob. 87PCh. 7 - There are many established nondimensional...Ch. 7 - Prob. 89CPCh. 7 - For each statement, choose whether the statement...Ch. 7 - Prob. 91PCh. 7 - Prob. 92PCh. 7 - Prob. 93PCh. 7 - The Archimedes number listed in Table 7-5 is...Ch. 7 - Prob. 95PCh. 7 - Prob. 96PCh. 7 - Prob. 98PCh. 7 - Prob. 99PCh. 7 - Repeal Prob. 7-100 except for a different...Ch. 7 - Prob. 101PCh. 7 - Prob. 102PCh. 7 - Au aerosol particle of characteristic size DPmoves...Ch. 7 - Prob. 104PCh. 7 - Prob. 105PCh. 7 - Prob. 106PCh. 7 - Prob. 107PCh. 7 - Prob. 108PCh. 7 - Prob. 109PCh. 7 - Prob. 110PCh. 7 - An electrostatic precipitator (ESP) is a device...Ch. 7 - Prob. 113PCh. 7 - Repeat pall (a) of Prob. 7-110, except instead of...Ch. 7 - Sound intensity I is defined as the acoustic power...Ch. 7 - Repeal Prob. 7-112, but with the distance r from...Ch. 7 - Engineers at MIT have developed a mechanical model...Ch. 7 - Prob. 118PCh. 7 - Prob. 119PCh. 7 - Prob. 120PCh. 7 - Prob. 121PCh. 7 - The primary dimensions of kinematic viscosity are...Ch. 7 - Prob. 123PCh. 7 - Prob. 124PCh. 7 - Prob. 125PCh. 7 - There at four additive terms in an equation, and...Ch. 7 - Prob. 127PCh. 7 - Prob. 128PCh. 7 - Prob. 129PCh. 7 - Which similarity condition is related to...Ch. 7 - A one-third scale model of a car is to be tested...Ch. 7 - A one-fourth scale model of a car is to be tested...Ch. 7 - A one-third scale model of an airplane is to be...Ch. 7 - Prob. 134PCh. 7 - Prob. 135PCh. 7 - Prob. 136PCh. 7 - Consider a boundary layer growing along a thin...Ch. 7 - Prob. 138P
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- When a sphere falls freely through a homogeneous fluid, it reaches a terminal velocity at which the weight of the sphere is balanced by the buoyant force and the frictional resistance of the fluid. Make a dimensional analysis of this problem and indicate how experimental data for this problem could be correlated. Neglect compressibility effects and the influence of surface roughness.arrow_forwardA one-fourth scale model of an airplane is to be tested in water. The airplane has a velocity of 700 km/h in air at −50°C. The water temperature in the test section is 10°C. In order to achieve similarity between the model and the prototype, the test is done at a water velocity of 393 km/h. The properties of air at 1 atm and −50°C: ? = 1.582 kg/m3, ? = 1.474 × 10−5 kg/m·s. The properties of water at 1 atm and 10°C: ? = 999.7 kg/m3, ? = 1.307 × 10−3 kg/m·s. If the average drag force on the model is measured to be 13,800 N, the drag force on the prototype is (a) 590 N (b) 862 N (c) 1109 N (d ) 4655 N (e) 3450 Narrow_forwardThe aerodynamic drag of a new sports car is to be predicted at a speed of 60 mph at an air temperature of 25°C. Automotive engineers build a one-third scale model of a car to test in a wind tunnel, shown in the figure below. The temperature of the wind tunnel air is also 25°C. The drag force is measured with a drag balance, and the moving belt is used to simulate the moving ground (from the car's frame of reference). The aerodynamic drag on the model in the wind tunnel is measured to be 34.5 lbf when the wind tunnel is operated at the speed that ensures similarity with the prototype car. Estimate the drag force (in lbf) on the prototype car at the given conditions. For air at T = 25°C and atmospheric pressure, p=1.184 kg/m3 and u-1.849-10-5 kg/m-s. Wind tunnel test section Pm Pm Fo.m Moving belt Drag balance The drag force on the prototype car is estimated to be Ibf.arrow_forward
- 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…arrow_forwardIn making a dimensional analysis, what rules do you followfor choosing your scaling variables?arrow_forwardThe aerodynamic drag of a new sports car is to be predicted at a speed of 60.0 mi/h at an air temperature of 25°C. Automotive engineers build a one-third scale model of the car to test in a wind tunnel. The temperature of the wind tunnel air is also 25°C. The drag force is measured with a drag balance, and the moving belt is used to simulate the moving ground (from the car’s frame of reference). Determine how fast the engineers should run the wind tunnel to achieve similarity between the model and the prototype.arrow_forward
- The aerodynamic drag of a new sports car is to be predicted at a speed of 60.0 mi/h at an air temperature of 25°C. Automotive engineers build a one-third scale model of the car to test in a wind tunnel. The temperature of the wind tunnel air is also 25°C. The drag force is measured with a drag balance, and the moving belt is used to simulate the moving ground (from the car’s frame of reference). Determine how fast the engineers should run the wind tunnel to achieve similarity between the model and the prototype.arrow_forward(COLLAB) Simulate projectile motion with air resistance in PhysLab. A shuttlecock is launched from the ground with an initial speed of 36.9688 m/s at an angle of 6.8583 degrees with respect to the horizontal. The shuttlecock experiences air resistance with a drag coefficient of 0.1931 in an environment where the air density is 0.9453 kg/m3. If the shuttlecock has a radius of 3.4 cm and a mass of 5.2 grams, what is the maximum height reached by the shuttlecock? Assume that the experiment is done near the surface of the earth (initHeight = 0) .arrow_forwardConsider a boundary layer growing along a thin flat plate. This problem involves the following parameters: boundary layer thickness ? , downstream distance x, free-stream velocity V, fluid density ? , and fluid viscosity ? . The number of primary dimensions represented in this problem is (a) 1 (b) 2 (c) 3 (d ) 4 (e) 5arrow_forward
- proto- 7-39 A student team is to design a human-powered subma- rine for a design competition. The overall length of the p type submarine is 2.24 m, and its student designers hope that it can travel fully submerged through water at 0.520 m/s. The water is freshwater (a lake) at T = 15°C. The design team builds a one-eighth scale model to test in their university's wind tunnel (Fig. P7-39). A shield surrounds the drag bal- V Po, P FLOUR Wind tunnel test section Model Shield E FD Drag balance Strutarrow_forwardThe drag of a sonar transducer is to be predicted, based on wind (Air) tunnel test data. The prototype is 1.5 m diameter sphere, is to be towed at 4.3 m/s in seawater. The model is 0.2 m diameter. Take: Air density = 1.2 kg/m, Air dynamic viscosity = 1.81 x 10$ Pa. s, seawater density = 1000 kg/m, seawater dynamic viscosity 1.813x 10 Pa s, If the drag of the model at these test conditions is 9.5 N, estimate the drag of the prototype in (N).arrow_forwardAn underwater device which is 2m long is to be moved at 4 m/sec. If a geometrically similar model 40 cm long is tested in a variable pressure wind tunnel at a speed of 60 m/sec with the following information, Poir at Standard atmospheric pressure = 1.18kg/m³ Pwater = 998kg/m3 Hair = 1.80 x 10-5 Pa-s at local atmospheric pressure and Hwater = 1 × 10-3 Pa-s then the pressure of the air in the model used times local atmospheric pressure isarrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning
Principles of Heat Transfer (Activate Learning wi...
Mechanical Engineering
ISBN:9781305387102
Author:Kreith, Frank; Manglik, Raj M.
Publisher:Cengage Learning
Unit Conversion the Easy Way (Dimensional Analysis); Author: ketzbook;https://www.youtube.com/watch?v=HRe1mire4Gc;License: Standard YouTube License, CC-BY