Final Review Questions

Final Review Questions - CENG l OlA - 2009 SAMPLE PROBLEMS...

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-- CENG lOlA - 2009 SAMPLE PROBLEMS D.M1LLER During the last week ofclass, on Tues and Wed, we will review the course material and go over sample problems. Please bring your texts to class. I have sketched some problems below which are typical ofthe type which may appear on the fmal. Please come to class prepared to answer a few ofthese, ofyour choice, ifyou are called upon. We will only have time to outline the approach you would take in most cases, i.e. indicate the method and which equation you would use, not to do the details with numbers. You may assume you would be given appropriate dimensions, properties, empirical CD, and equations or that the final is open book. Example Questions I. Answer Briefly~ Since a rough surface increases friction and a turbulent flow has a larger effective viscosity than a laminar flow, which should also increase friction shear forces, discuss briefly why dimpled golfballs have less drag and therefore go farther than smooth balls ofthe same size and weight. Why does streamlining a body sometimes reduce and sometimes increase the drag? 2. Answer Briefly: List the assumptions necessary to obtain the Navier-Stokes equations What is the difference between an Eulerian and a Lagrangian description of fluid mechanics, and what is the difference between a control system and a control volume. What is the buoyancy force due to? From what Law is the extended Bernoulli equation derived? When is it valid only along a streamline? 3. Answer Briefly: Discuss why does the water jet goes much fwther when you place your thumb over the garden hose exit and decrease the exit area? What are the Reynold's stresses, where do they come from, and when are they important. 4. Estimate the fluid velocity for transition from laminar to turbulent flow ifthe pipe diameter is I cm and the fluid is: (a) water; (b) air . Does the result depend on whether the pipe is vertical or horizontal? 5. Derive a relation between the absolute pressure at any altitude h and the absolute pressure at sea level, given as P = Po at y = 0 . Assume air is an ideal gas P = pRT , and assume the atmosphere is isothermal (RT = constant). 6. A
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This note was uploaded on 10/24/2010 for the course CENG 101 taught by Professor Staff during the Fall '08 term at UCSD.

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Final Review Questions - CENG l OlA - 2009 SAMPLE PROBLEMS...

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