# User talk:Bcebul

Hi Bcebul, and welcome to Wikipedia! Thanks for your contributions to the coolest online encyclopedia I know of =). I sure hope you stick around; we're always in need of more people to create new articles and improve the ones we already have. You'll probably find it easiest to start with a tutorial of how the wikipedia works, and you can test stuff for yourself in the sandbox. When you're contributing, you'll probably find the manual of style to be helpful, and you'll also want to remember a couple important guidelines. First, write from a neutral point of view, second, be bold in editing pages, and third, use wikiquette. Those are probably the most important ones, and you can take a look at some others at the policies and guidelines page. You might also be interested in how to write a great article and possibly adding some images to your articles.

Be sure to get involved in the community – you can contact me at my talk page if you have any questions, and you can check out the village pump, where lots of wikipedians hang out and discuss things. If you're looking for something to do, check out the community portal. And whenever you ask a question or post something on a talk page, be sure to sign your name by typing ~~~~.

Again, welcome! It's great to have you. Happy editing! --Spangineer (háblame) 11:05, Jun 11, 2005 (UTC)

Hi,
I need your help. I am working on a research project at Boston College, studying creation of medical information on Wikipedia. You are being contacted, because you have been identified as an important contributor to one or more articles.

Would you will be willing to answer a few questions about your experience? We've done considerable background research, but we would also like to gather the insight of the actual editors. Details about the project can be found at the user page of the project leader, geraldckane. Survey questions can be found at geraldckane/medsurvey. Your privacy and confidentiality will be strictly protected!

The questions should only take a few minutes. I hope you will be willing to complete the survey, as we do value your insight. Please do not hesitate to contact me or Professor Kane if you have any questions.

Thank You, BCeagle0312 (talk) 19:44, 9 July 2008 (UTC)

## Kutta-Joukowski

Hi Bcebul. Thanks for your recent edits to Lift (force). I noticed your edit summary regarding the disproven Kutta-Zhukovsky theorem. The editors who edit this article regularly and who monitor its progress certainly don't regard the Kutta-Joukowski theorem as being disproven. If you continue with this line of thought it is inevitable that some of your work will be reverted. Please use the Talk:Lift (force) page to discuss things you want to eliminate from the article, and particularly if the article states something that you consider to be disproven or scientifically incorrect. Best regards. Dolphin (t) 03:31, 31 March 2011 (UTC)

Thanks. Take it up with Hoffman and Johnson who have published their work in a peer reviewed journal: J. Hoffman and C. Johnson, Resolution of d´Alembert's paradox, Online First, Dec 10, 2008, Journal of Mathematical Fluid Mechanics. Journal of Mathematical Fluid Mechanics Sept 12 2008. Bcebul (talk) 05:30, 31 March 2011 (UTC)

No, neither Hoffman nor Johnson has posted anything on Wikipedia so we won't be taking anything up with them. You have posted things on Wikipedia so if Users want to discuss any of your contributions they will discuss them with you. We are all responsible for everything we post on Wikipedia and that is one of the reasons we all need to be confident we have suitable published sources for the material we add, so it can be independently verified and so we can discuss it with other Users. Cheers. Dolphin (t) 06:27, 31 March 2011 (UTC)

## Bernoulli's principle

Hi Bcebul. On 10 June you made an edit to indicate that Bernoulli's principle states that an increase in speed occurs simultaneously with an increase in dynamic pressure and an increase in kinetic energy. I have reverted your edit. I agree that an increase in speed occurs simultaneously with an increase in kinetic energy - that is the consequence of the definition of kinetic energy. Similarly, an increase in the speed of a fluid occurs simultaneously with an an increase in dynamic pressure - that is the consequence of the definition of dynamic pressure. Neither of these changes is linked to the discovery by Bernoulli, now known as Bernoulli's principle. The statement which you edited is supported by citation of the book Aerodynamics by L.J. Clancy. This book does not support the changes you made.
Your interest in fluid dynamics subjects is much appreciated. Keep going! Please don't be disheartened by my reverting of your good-faith edits. Dolphin (t) 02:15, 10 June 2011 (UTC)

Thanks. If Bernoulli's principle implies (rather than says) what I wrote and what is stated later in the article leading to the incompressible flow equation: ${\displaystyle p_{0}\,=\,p\,+\,q\,}$ , then perhaps this important implication and distinction could be introduced earlier for the sake of clarity?Bcebul (talk) 03:10, 10 June 2011 (UTC)

I'm not sure I understand your comment. Dynamic pressure is defined in terms of fluid speed (and density) at Dynamic pressure and also at Bernoulli's principle. Kinetic energy is defined in terms of speed (and mass) at Kinetic energy. What are you suggesting could be introduced earlier in the article for the sake of clarity? Dolphin (t) 03:57, 10 June 2011 (UTC)
Well, in hindsight, the "pressure" Bernoulli was referring to which was decreased by increasing velocity of the fluid was static pressure. The decrease in potential energy he apparently noted, by the first law of thermodynamics, implies increase in kinetic energy, etc. He may have pre dated the 1st law, but we have known it since 1850. Why not come to the point earlier in the article for the practical, erudite education of the reader? Bcebul (talk) 05:41, 10 June 2011 (UTC)
The first sentence in the article says:
In fluid dynamics, Bernoulli's principle states that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy.
That seems to summarise it quite well, but if you think the article needs some extra information earlier in the article you could refine the first sentence. Dolphin (t) 06:11, 10 June 2011 (UTC)

Thanks for uploading File:AllureEnglish.jpg. You don't seem to have indicated the license status of the image. Wikipedia uses a set of image copyright tags to indicate this information.

To add a tag to the image, select the appropriate tag from this list, click on this link, then click "Edit this page" and add the tag to the image's description. If there doesn't seem to be a suitable tag, the image is probably not appropriate for use on Wikipedia. For help in choosing the correct tag, or for any other questions, leave a message on Wikipedia:Media copyright questions. Thank you for your cooperation. --ImageTaggingBot (talk) 02:05, 11 June 2011 (UTC)

## Forces on sails

Lift direction is usually defined as perpendicular to the flow and drag parallel to flow of apparent wind.

Fully agree with you !

i have make the correction thanks to our picture on wp:fr.

My english is not fluent, i am not able to translate Forces on sails part Several sails: multidimensional problem resolution in a correct US language.

If you are agree we can make this job together (i can help you to translate or the reverse ).

best regards Erwan1972 (talk) 15:37, 21 June 2011 (UTC)

Please note that we are having a discussion on the Sail talk page regarding how best to explain the matter. We would welcome your comments on the talk page, since we are developing consensus text that will then be placed in the article, see Talk:Sail#Thrust.3F.--Gautier lebon (talk) 07:21, 22 June 2011 (UTC)

### Invitation

Hi Bcebul. Thank you for your editing at Forces on sails. As discussed there, I am proposing to re-organize the article, using much of the existing material, in order to make the article more accessible. I hope that you will participate. So, I invite you to follow the sandbox page where the reorganization is being drafted. I suggest making comments on that effort at Talk:Forces on sails#Reorganization?. Sincerely, User:HopsonRoad 15:35, 10 March 2015 (UTC)

## Recent edits to naval architecture article

Hi Bcebul Thanks for your edits to the naval architecture article. Although aerodynamics is a main subject in yacht design, it is not so in naval architecture. The article primarily deals with the subject of naval architecture itself and not the design of specific types of vessels. Please feel free to discuss in the article's talk page. ChrysalSnowlax (talk) 03:16, 22 September 2011 (UTC)

Thanks, ChrysalSnowlax. That is nonsense. Naval architecture institutions traditionally and to date include aerodynamics in their curricula, as they must due to the fundamental effects of air movement affecting weather, waves and vessels of all sorts, sail or not. To ignore this fact is to make the article incomplete. Also, sailboat design is an important traditional and current aspect of naval architecture and is included in the discipline. Just because some institutions or naval architects may not focus on aerodynamics or limit their curricula from time to time or trend to trend, does not change the fundamentals. See references which you have deleted. Bcebul (talk) 07:41, 12 October 2011 (UTC)

Hi Bcebul, it's not nonsense. I did check all the references you provided. Two of them were books on sail boat and yacht design respectively.
If you can provide a reference of a textbook on core naval architecture OR a link from any of the accredited professional organisations (RINA, SNAME, ASNE or IMarEST) which mentions aerodynamics as a main subject of naval architecture, then it would be worth including it in the article.
The third reference you provided was a course guide of naval architecture from Australian Maritime College, which listed 'fluid mechanics'. The subjects listed in the above course guide are typical of naval architecture curriculum of other institutions.
I understand that you mention aerodynamics as a part of 'fluid mechanics'.
However, 'fluid mechanics' is not taught as a subject of naval architecture itself but as a topic in basic engineering (similar to ‘solid mechanics’).
You will find 'fluid mechanics' listed in the course guides of other engineering branches, say for example, civil engineering or even instrumentation and control engineering. This does not mean 'fluid mechanics' is a main subject of civil engineering.
As I mentioned previously, the article primarily deals with naval architecture as a branch of engineering and the main subjects of naval architecture are those presently given there. Feel free to discuss. ChrysalSnowlax (talk) 02:24, 13 October 2011 (UTC)
Fluid mechanics and Fluid dynamics include aerodynamics. Maybe "Main Subjects" is an inappropriately narrow, limiting and arbitrary heading not inclusive of all Naval Architecture curricula. Change it to include topics of interest in Naval Architecture. Sheesh:

from: http://name.engin.umich.edu/ugrad_course_list NAVARCH 403. Sailing Craft Design Principles

Prerequisite: preceded or accompanied by NA 321. II (4 credits)

Forces and moments acting on a sailing yacht. Speed polar diagrams. Two- and three-dimensional >>>airfoil theory<<<<. Application to keel and rudder design. >>>>Yacht model testing. Delft Standard Series for prediction of hydrodynamic performance. >>>>Aerodynamics<<<< of yacht sails. Sail force coefficients. Velocity Prediction Program. Rigging design and analysis. Yacht racing rules.

and from http://www.amc.edu.au/areas-study Naval Architecture: Naval architects are professional engineers that design and oversee the construction and repair of marine craft and various offshore structures. This includes naval craft, passenger and cargo ships, submarines, high-speed ferries and catamarans, tugs, >>>>yachts<<<< and offshore drilling platforms. and http://www.amc.edu.au/maritime-engineering/course/bachelor-engineering-naval-architecture Course structure

This course is structured to be completed in 4 years of full-time study and consists of 8 subjects per year of study. Students meeting the required standards of achievement throughout the course may qualify for an Honours award.

Year 1

```   Mathematics I
Design and Computer Aided Drafting (CAD)
Programming and Problem Solving for Engineers
Statics
Materials Technology
Mathematics II
Dynamics
Electrical Fundamentals
```

Year 2

```   Calculus of Several variables
Thermal Engineering
Project Engineering
Hydrostatics
Ship Production
Ship Design
Mechanics of Solids
```

>>>>> Fluid Mechanics

Year 3

```   Materials of Engineering Design
Structural Analysis
Ship Resistance and Propulsion
Noise and Vibration
Ship Dynamics
Applied Ship Design
Hydrodynamics
Finite Element Analysis
```

Year 4

```   Advanced Ship Structures
Ocean Vehicle Design Project (Part 1 & 2)
Research Project (Part 1 & 2)
Design of Marine Machinery Systems
```

>>>>>> Yacht Design and Technology (Elective) OR

```   Applied Computational Fluid Dynamics (Elective)
```

and http://oe.mit.edu/index.php?option=com_content&task=view&id=37&Itemid=41 SB in Mechanical and Ocean Engineering

The Bachelor of Science in Mechanical and Ocean Engineering is designed for students who are interested in mechanical engineering with a specialization in ocean engineering. Within the MIT community this course is called 2-OE.

The program incorporates aspects of ocean exploration and utilization of the oceans for transportation, defense, and resources. Courses and research >>>>>covers the disciplines of >>>>fluid dynamics<<<<<, structural mechanics, acoustics, dynamics, materials, and ocean systems and design. The degree prepares students for work in the industry and government in areas including offshore oil recovery, transportation and defense, ocean environment protection, underwater vehicles, global climate monitoring, and computer-aided design. For more information on the degree, visit the Department of Mechanical Engineering.

and http://www.rina.org.uk/ijsct.html >>>>International Journal of Small Craft Technology Bcebul (talk) 10:35, 13 October 2011 (UTC)

Hi Bcebul, you are again focusing on sailing craft. The point of the article is to cover the branch of naval architecture and not specific types of vessels. Types of vessels designed by naval architects are already mentioned in the article.
The references you have given do not say that studying aerodynamics is a must to become a naval architect. 'Fluid mechanics' is not taught as a subject of naval architecture itself but as a topic in basic engineering (similar to 'solid mechanics') (Check up course guides of mechanical engineering, civil engineering, mechatronics, aerospace engineering, instrumentation and control engineering, industrial and production engineering etc). I would appreciate it if you read my previous posts carefully. ChrysalSnowlax (talk) 04:58, 17 October 2011 (UTC)

## Drag (physics)

Hello Bcebul. Today you made some edits to Drag (physics). (See your diff.)

I have deleted your paragraph which stated: Depending on the direction of the velocity of the solid relative to the fluid (a liquid or gas), the drag may be the component of the net aerodynamic or hydrodynamic force acting opposite to the direction of the movement such as in a car or aeroplane, or it may act in the same direction of motion as the solid, such as in a boat sailing down wind.

I deleted it for two reasons:

• The paragraph was unsourced. Information on Wikipedia must come from reliable, published sources. The source must be cited to allow independent verification and to guard against editors adding material that they believe to be true but which is not true and has never been published in a reliable source.
• The content of the paragraph was incorrect. It is misleading to say that, in the case of a boat sailing down wind, the drag acts in the same direction as the boat. Drag acting on a solid body always acts to oppose the motion of that body through the fluid. It is true that drag can sometimes act in a direction that enhances the motion of a solid body relative to the Earth's surface, such a boat or a paper bag accelerating across the Earth's surface as a result of the aerodynamic drag caused by the wind. But lift and drag are never defined in terms of motion relative to the Earth's surface - they are always defined in terms of motion relative to a fluid.

You are free to add information to Drag (physics) when you are able to cite the source or sources from which you obtained the information. Happy editing. Dolphin (t) 04:59, 16 October 2011 (UTC)

Thanks Dolphin. Correct, drag is always defined in terms of motion relative to a fluid. It is a force on the solid exerted by the fluid in the direction of the fluid's motion relative to the solid. That is all. There is no part of the definition mentioning the direction of the solid's motion or opposition to or enhancement of the solid's motion. The paragraph in question is only there to illustrate practical application of drag theory. Citations added as requested.Bcebul (talk) 10:08, 16 October 2011 (UTC)

I have raised the matter for discussion among Users who have an interest in the subject. See Talk:Drag (physics)#Direction of action of drag. Please add your own comments to the new thread. Dolphin (t) 11:42, 16 October 2011 (UTC)

Please be very careful with your additions to Drag (physics). I don't think your additions have improved the quality of the article. In one of your recent edits you added the following sentence: In the case of laminar flow of fluid in a pipe, viscous drag force on the immobile pipe decreases the magnitude of fluid flow in a direction opposite to the drag force direction. I assume that by the expression the magnitude of fluid flow you mean the flow rate as might be measured in gallons per minute or litres per second or pounds per second. I’m sure you are aware that fluid flow rate is a scalar quantity - it doesn't have direction in the way vectors do. If the rate of fluid flow decreases it is sufficient to say it decreases - it isn't meaningful to say it decreases in one direction or the other.

The rate of fluid flow through a pipe will be affected by the drag, regardless of whether the flow is laminar or turbulent. Adding the words in a direction opposite to the drag force is unnecessary and unhelpful. Dolphin (t) 01:55, 17 October 2011 (UTC)

## Tweaks suggested for your excellent illustrations

Hi Bcebul. Thanks for providing and evolving your excellent illustrations on forces that affect a sailboat, File:Boatforcestop.svg and File:Boatforcestern.svg. They appear to have a transparent background, which in some cases renders as a distracting checkerboard pattern. It would be enormously helpful, if you could put a solid background behind them. I could do this in Photoshop, but I'm afraid to destroy your ability to edit the top layer.

Also, I could suggest rendering the mainsail opaque in File:Boatforcestop.svg. This would hide the distracting gunnel visible through it in the current version. Cheers, User:HopsonRoad 12:56, 13 March 2015 (UTC)

## Discussion of Wikimedia

Hi Bcebul. Thanks for your suggestions on the Cl and Cd diagram at Wikimedia. I have more thoughts there. Cheers, User:HopsonRoad 22:03, 27 March 2015 (UTC)

## Forces on sails

Hi Bcebul, I'd like to invite you to help me solve the issues that various editors have raised at Talk:Forces on sails.

I can tell that working on this article gives you great pleasure and satisfaction, which I also derive from my editing activities. Editing gives an opportunity both to learn for oneself and to teach others—both of which can be very satisfying. Such dedication, unfortunately, has the risk of a sense of ownership of an article. I can tell from the civility of your responses in talk pages that you are a person of WP:Good faith. It would be great, however, to see more participation in discussion. I note that, of your last 500 edits, only 28 of them were at the Talk:Forces on sails page. I feel that you are trying to be responsive to ideas that I post there—harmonizing nomenclature and incorporating diagrams—but I'm concerned that you have missed the bigger concern about how to make technical articles understandable (see this link). You'll note that I have tried to follow that guidance in the sandbox, especially the "Rules of thumb":

• 4.1 Put the most understandable parts of the article up front
• 4.2 Write one level down
• 4.3 Add a concrete example
• 4.4 Explain formulae in English
• 4.6 Avoid overly technical language
• 4.7 Don't oversimplify:

I wanted to have this conversation with you, because the alternative seems to be major remodeling of what you have worked on without your participation and that would make you feel bad and lead to edit warring and, ultimately, arbitration. I don't want that for either of us.

So, I can suggest two approaches, both of which involve a hiatus in working directly in the article: 1. let's discuss the article at the Talk:Forces on sails page in light of Wikipedia:Make technical articles understandable and/or 2. let's do further editing in the sandbox.

How about a joint goal of making this a WP:Good Article? There are only two in Wikipedia:WikiProject Sailing, one of which looks dubious to me!

Sincerely, User:HopsonRoad 12:01, 28 March 2015 (UTC)

## ArbCom elections are now open!

Hi,
You appear to be eligible to vote in the current Arbitration Committee election. The Arbitration Committee is the panel of editors responsible for conducting the Wikipedia arbitration process. It has the authority to enact binding solutions for disputes between editors, primarily related to serious behavioural issues that the community has been unable to resolve. This includes the ability to impose site bans, topic bans, editing restrictions, and other measures needed to maintain our editing environment. The arbitration policy describes the Committee's roles and responsibilities in greater detail. If you wish to participate, you are welcome to review the candidates' statements and submit your choices on the voting page. For the Election committee, MediaWiki message delivery (talk) 13:05, 23 November 2015 (UTC)