Drag Force Calculations for Flow Over an Elliptic Cylinder

Use pressure along the surface of the ellipse from the potential flow solution:

Use wall shear stress along the surface of the ellipse from the laminar boundary layers solution:

Ellipse top surface is divided up into 10000 points. Separation occurs at point 8279.

FLUIDS 420/520 PROBLEM SET 5

PART 1: READING CRITIQUE ON TURBULENCE FALL 2017

Finish your reading critique for the beginning of class on, Tuesday, October 10th. Bring your reading critique with you to class. We will have a class discussion that day and I will be calling on you for input. Estimated time for you to do the reading and to do the discussion questions is two to three hours. For E.O. students finish your reading critique before viewing class session 15. Suggested approach: Read all the articles that are posted under the problem set link of the course Internet site- then work on the discussion questions. You may also use Wikipedia or other references – but be sure to cite the reference that you use. Different authors will have different points of view on some of the topics! You should also read sections 6.1 and 6.2 in the Frank White text.

1. Give at least three characteristics of turbulence.

2. Define the following terms with regard to turbulent flow. Use examples when possible.

• Reynolds decomposition • Closure problem • Isotropic turbulence • Coherent structure • Turbulence models • Reynolds averaged Navier-Stokes (RANS) • Large eddy simulation (LES) • Direct numerical simulation (DNS)

Discuss typical applications and limitations of the last three.

3. Which of these would we be most likely to find in a commercially available computational fluid dynamics code with turbulent flow capability? (a) a fractal theory of turbulence, (b) k-ε turbulence model, (c) direct numerical simulation.

4. List two turbulence models and a typical application of each.

5. Discuss a few points that surprised or interested you in the articles.

Leave some extra space on the pages where you answer these questions. A part of problem set is for you to add to you answers from what we learn from each other during the class session. I will want you to mark the answers that you had at the beginning of class (with your initials) and the ones that you added during our class discussion session (with the word “class”). PART 2: PROJECT IDEAS Please submit at least two project concepts that are of interest to you. I would like a paragraph (between 100 and 200 words) on each project concept. Feel free to contact me by email if you want to get some feedback when you are writing the project concept paragraphs.

Boise Students: Hand-in or scan and send part 1 and part 2 to me by Friday, October 13th. Moscow Students: Send me part 1 or hand it in by 4:00 pm (to Becky) by Friday, October 13th. Send me part

2 to me by email by Friday, October 13th. Engineering Outreach students - please email reading critique within one week of viewing the in-class

discussion. Email me part 2 as well. I hope to receive both from you by Monday, October 16th.

FLUIDS 420/520 SCHEDULE

Weeks One Through Eight

Fall Semester 2017

Last Updated September 28, 2017

Week of Activity Resources

Aug 20

&

Aug 27

Course introduction

Introduction to model problem 1

Review of external flow over objects

Ideal flow over a circular cylinder

Streamlines

Vector plots

Posted materials

Undergraduate fluids text and 1-2

Posted materials and 4-1

Posted materials

Posted materials and 2-11

Sept 3 Particle pathlines

The governing equations of fluid flow

Ideal flow over an elliptic cylinder

Posted materials

Posted materials, 2-3, and 2-4

Posted materials

Sept 10 The pressure field

Surface velocity plot

Review of boundary layers

Posted materials

Undergraduate fluids text, 4-1, 4-3,

and 4-3.1

Sept 17 Review of boundary layers

Boundary layer calculation for flow

over an elliptic cylinder

Posted materials, 5-4.2, and 5-4.3

Posted materials, 4-2.1, 4-6.1, and 4-

6.2

Sept 24 Boundary layer calculation for flow

over an elliptic cylinder

Posted materials and 4-6.6

Oct 1 Separation, skin friction drag, and

form drag for flow over an elliptic

cylinder

Performing a knowledge search for

an engineering project

Review of dimensional analysis

Low Reynolds number flow

Class project

Posted materials and 4-2.2

Posted materials

Undergraduate fluids text

Posted materials

Posted materials

Oct 8 Turbulence reading critique

Dimensional analysis, similitude, and

scaling

See Problem Set 5

Undergraduate fluids text and posted

materials

FLUIDS 420/520 SCHEDULE

Weeks Eight through Fifteen

Fall Semester 2017

Last Updated September 28, 2017

Week Activity Resources

Oct 8 Turbulence reading critique

Dimensional analysis, similitude, and

scaling

See Problem Set 5

Undergraduate fluids text and posted

materials

Oct 15 Turbulence short course Posted materials and 6-1 and 6-2

Oct 22 Turbulence short course

Ellipse flow with turbulent b.l.

No class session on October 26th

Posted materials and 6-1 and 6-2

Posted materials and 6-8

Oct 29 Open channel flow Undergraduate fluids text and posted

materials

Nov 5 Open channel flow Undergraduate fluids text and posted

materials

Nov 12 Open channel flow Undergraduate fluids text and posted

materials

Nov 19 Thanksgiving break

Nov 26 TBD

Dec 3 Project Presentations

Dec 10 No class meetings this week (finals

week). All project reports due to RB

by December 15th.

PERFORMING A KNOWLEDGE SEARCH FOR AN ENGINEERING PROJECT

Fluids 420/520 October 1, 2017

Examples on this handout will be given in various sub-areas of Fluid Dynamics – but the same

principles apply to other engineering and science sub-areas. This handout is divided into two

parts: Part 1 describes an approach to perform a knowledge search, and Part 2 gives detailed

instructions on using UI Library resources through the Internet.

Part 1: Knowledge Search Strategy

Level 1 – Develop a basic understanding of the terms and physics of simple problems that are

related to your specific problem.

Resources:

Your undergraduate fluids textbook

Internet sites: Google web or image search, Wikipedia, HowStuffWorks, etc.

Other useful texts in fluids are the Applied Fluid Dynamics Handbook by Robert D. Blevins and

the Handbook of Fluid Dynamics, edited by Richard W. Johnson. Both books are available from

the UI Library.

For example – suppose you are interested in race car aerodynamics. Review the chapter on drag

and lift in your undergraduate fluids text.

Level 2 – Obtain background information on the specific research problem that you are studying.

Resources:

Try to find a book that specializes on the area of your research problem. You can use the

UI Library Catalog or WorldCat, which is an excellent search engine to find specialized

books. Once you find a book that is relevant then you should go to the library and scan

the bookshelf to the left and right of the book that you found in the search engine. You

probably will find additional books that are of even more relevance.

Find a review article on your problem. In the fluids area the Annual Review of Fluid

Mechanics (ARFM) is an excellent resource and is available on line at the UI Library

Internet site. Use the “Journal” link on the library home page to find it. Review articles

can also be found using Compendex or Web of Science (see Level 3 below).

For example – suppose you are investigating flow in stenotic coronary arteries. A scan of

ARFM articles reveals a 2000 review article entitled, “Flow in Stenotic Vessels” by Berger and

Jou.

Level 3 – Obtain detailed information on your specific research problem.

Resources:

Look up key publications that are sited in the book or review article that you found in

your Level 2 search. Many of these journal publications may now viewed directly

through the UI Library Internet site.

Use search engines like Compendex, Web of Science, or Google Scholar to find articles.

You can also go to professional society sites to search for articles (for example, ASCE or

ASME). Determining the correct keywords for your topic can be challenging.

Warning – skipping levels 1 and 2 will often yield a, “I can’t see the forest for the trees,” mindset. You are also

much more likely to end up going down the primrose path by going straight to level 3.

You can save time by visiting with a professor (or some other expert) who works in the area related to your search.

They can give you the names of the most relevant books, review articles, and research papers.

Librarians can help you pick the most relevant search engines for your project. They can also help you in the use of

search engines. For help with any of these levels, contact directly Evan Peter Williamson, the UI Engineering

librarian, at ewilliamson@uidaho.edu or 208-885-6260.

Part 2: Using UI Library Resources through the Internet

1. In order to do use the many useful functions of the UI Library through the Internet you simply use

your UI login and password – the same one you use to get into Vandalweb or access your email. If

you are having difficulty with this please see the distance education guide at: http://libguides.uidaho.edu/Distance_Education?hs=a

and contact Rami Attebury (208 885 2503) as need be.

2. The entry point to search for books in is on the home page under the text, “Advanced Search”. This

will take you to page where you can specify keywords, titles, etc. You can specify UI Library or UI+

Summit (regional libraries). When you do a search you will have the option to show what is available

at the library and what is provided as “full text online”. Another useful tool for book searches is

“WorldCat”. The link to WorldCat is found on the home page.

3. The entry point to search for articles is the link, “Find: Articles and Databases” located on the home

page. Click on this to locate the links to search engines like Compendex or Web of Science.

4. Once you have located the reference for an article you may be able to obtain the article directly:

a. By clicking on the “Find It” icon or link that is shown in many databases like Compendex

or Web of Science. This will take you directly to the article in many cases. If not, there

may be other choices given to either get to the full text, to the library’s holdings for the

journal, or for Interlibrary Loan. Note: in some databases, the link to library holdings is

shown as “Locate Article”.

b. By going to the link, “Journals” on the UI Library home page. You will then type the

title of the journal. This will bring up information on whether or not UI has electronic

access to the journal. For example, type Journal of Biomechanics and you will see that

UI has electronic access from 1995 forward. If the paper that you need is available by

electronic access then click on the provided link and then search for the year and page

numbers of the paper. Then download a PDF file of the paper. If there is not electronic

access then use UI Interlibrary Loan to obtain the article. Note that the “Journals” link is

where you can find the Annual Review of Fluid Mechanics and other annual reviews.

5. You may also use Google Scholar to find articles and reviews. For students using a computer on a UI

campus, decide on the relevant keywords and then enter them into Google Scholar. Articles that are

available as PDF files will appear with a “Get it” after the article title and authors. For off-campus

computers the following steps will work. Google Scholar Search Scholar Click on three bar

pull down menu at upper left of screen Settings Library Link (Enter University of Idaho and

login) (you should obtain response with “Univ of Idaho – Get it”) go back to Google Scholar

(enter your keywords).

6. Interlibrary Loan. You may obtain any paper you need through Interlibrary Loan (ILL). The link to

Interlibrary Loan in found under “Quick Links” at the top of the UI Library home page. This will

bring up username and password entry boxes. If you are a first time user of Interlibrary Loan then go

to the “Setting Up Your ILL Account” link at the middle of the page. Enter your barcode number as

the username and the password that you selected. This will bring up a page with several links on the

left. Click on the “Article” link under the “New Requests” heading. Then fill out the information on

the article that you want. You will receive the article as a PDF file by email – usually within two

business days of making the request.