Talk:Entrance length (fluid dynamics)

Untitled
The article lacks sources for most claims in the article text and information displayed in the illustrations. Source 3 is included within the reference section, but not attached to any claims in the article. The three sources in the reference section are good and unbiased, but additional sources and better citation of the sources within the text is needed. Adding punctuation and rephrasing confusing sentences can improve readability. Specifically, phrases containing “we” such as “We can see in this image” should be removed. The section on Average Velocity focuses on velocity in the fully developed flow region (not the entry region) and may be better placed in a different fluid mechanics article. Also, the article can be linked to additional fluid mechanics articles such as Fluid Dynamics, Prandtl Number, Reynolds Number, Nusselt Number, Laminar Flow, and Turbulent Flow. Additional content may be added that provides a more detailed description of entry length and when the entrance region is considered to have transitioned into the region with developed flow. Discussion about importance of entrance length and its context in fluid mechanics is needed.

Krbuw (talk) 03:34, 14 January 2017 (UTC)

Planned additions to article

I'm planning on adding several sections that focus on better describing the characteristics and mathematics of entrance length. Possible topics include: Boundary Layer, Hydrodynamic Entry Region, Laminar Flow, Turbulent Flow, Effect on Heat Transfer, Relation to pipe and fluid conditions, Derivation, and additional descriptions about each of the regions located around the entry region. I will also add sections focusing on the importance of entrance length and the topic's context in engineering and fluid mechanics. I will discuss the importance of entrance length for calculation and design. One example I found was for accounting for entrance length when positioning flow instrumentation. I will also explore the circumstances when entrance length is relevant to calculations. Finally, entrance length will be given context in it's relationship to other fluid mechanics topics such as Reynolds Number, Prandtl Number, Nusselt Number, Turbulence, head loss, velocity profiles, and others.

Potential sources for additions

1. 1924-, Stewart, Warren E.,; 1925-, Lightfoot, Edwin N., (2002-01-01). Transport phenomena. J. Wiley. ISBN 0471410772. OCLC 46456316.

2. L., Bergman, T.; P., Incropera, Frank (2011-01-01). Fundamentals of heat and mass transfer. Wiley. ISBN 9780470501979. OCLC 713621645.

3. 1961-, Lienhard, John H., (2011-01-01). A heat transfer textbook. Dover Publications. ISBN 9780486479316. OCLC 853622802.

4. M., Cimbala, John (2006-01-01). Fluid mechanics : fundamentals and applications. McGraw-HillHigher Education. ISBN 0072472367. OCLC 56481360.

5. 1939-, Okiishi, T. H. (Theodore Hisao),; W., Huebsch, Wade; 1959-, Rothmayer, Alric P.,. Fundamentals of fluid mechanics. John Wiley & Sons, Inc. ISBN 1118399714. OCLC 781279071.

6. M., Cohen, Ira (2008-01-01). Fluid mechanics. Academic Press. ISBN 9780123737359. OCLC 647911370.

7. Taher., Schobeiri, Mohammed (2010-01-01). Fluid Mechanics for Engineers A Graduate Textbook. Springer Berlin. ISBN 3642115934. OCLC 873659245.

8. Marghitu, Dan (2001). Mechanical Engineer's Handbook. Elsevier

The article reads pretty good, grammar is good. There are some sections where it seems like it may be missing sources, such as the boundary layer and some of the equations that are used. The use of graphics is very helpful in explaining the topic. I am unsure if they are your own graphics are if they are sourced. It sounds like you plan on adding how entrance length applies to engineering which should be a good addition to the topic. Overall you have good sources with very few missing it seems. — Preceding unsigned comment added by Rmason81 (talk • contribs) 22:22, 14 February 2017 (UTC)

Wiki Education Foundation-supported course assignment
This article is or was the subject of a Wiki Education Foundation-supported course assignment. Further details are available on the course page. Student editor(s): Krbuw. Peer reviewers: Rmason81, MissAndrea.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 20:45, 17 January 2022 (UTC)

Peer Review Response(To Rmason81)
Thanks for the review Rmason81. Much of the content for the hydrodynamic entrance length came from an author from many years ago and is based off of one textbook. I'll cite the claims that are made and add additional sources. The graphics are from another Wikipedian, but the info they are based on appears to come from Fluid mechanics : fundamentals and application, I'm currently researching and writing about applications. It is difficult because entrance length/entry region is rarely mentioned by name. Looking into wind tunnel design and heat transfer applications.

Krbuw (talk) 02:38, 23 February 2017 (UTC)

Peer Review
Hello Krbuw,

For the purpose of this class, I've moved my peer review from your sandbox to here.

-Good start on your article! -I like that the language is encyclopedia and objective. -Overall, the spelling, grammar, and sentence structures look sound, and I like that the lead section has concise sentences (for example, the definition of entrance length). -I would expand on your subheading "Thermal Entrance Length" (cover any content gaps) and define the variables in that equation. -Also, I would find more sources for the content under "Average velocity," "Entry Length for Pipes with Noncircular Crossections," "Shear Stress," and "Boundary layers."

MissAndrea (talk) 04:09, 14 February 2017 (UTC)

MissAndrea (talk) 19:25, 25 February 2017 (UTC)

Peer Review Response(To MissAndrea)
Thanks for the review MissAndrea. You can see the article on the Wikipedia main page. I'm filling in the content gaps and improving the citations for existing content. I'm trying my best on the lead page to keep the definition of entrance length general. Most sources seem to focus on hydrodynamic entrance length. Much of the content for the hydrodynamic entrance length came from an author from many years ago and is based off of one textbook. I'll cite the claims that are made and add additional sources. The graphics are from another Wikipedian, but the info they are based on appears to come from Fluid mechanics : fundamentals and application, I'm currently researching and writing about applications. It is difficult because entrance length/entry region is rarely mentioned by name. Looking into wind tunnel design and heat transfer applications. Krbuw (talk) 02:45, 23 February 2017 (UTC) Krbuw (talk) 05:32, 27 February 2017 (UTC)

Addressing the need for a proper article title
The title of the article is "Entrance Length." Wikipedia notes the article needs a proper title. Before I began editing the page, the content in the article could have been best represented with the titles:"Hydraulic Entrance Length" or "Hydraulic Entrance Region" rather than "Entrance Length."

I developed the article and expanded its content to reflect the title. I wrote for a generalized "entrance length" that included multiple types of entrance length, not just hydraulic. The current article reflects the title "Entrance length" well.

If someone wanted to further generalize the article, the title "Entrance Region" may be appropriate, as there is no article for entrance region and this current article is the best resource on Wikipedia for learning about the "Entrance Region."

However, many online information resources use entrance length as a title for content that covers entrance region and entrance length. I checked the online search frequency for "Entrance Length" and "Entrance region," and entrance length is significantly more popular. An article entitled "Entrance Length" will have increased exposure and be easier to locate for most information seekers.

My current recommendation is for the title of the article to stay as "Entrance Length."

Krbuw (talk) 01:55, 11 March 2017 (UTC)


 * I think that the title should be changed to something like Developing Flow, Fully Developed Flow, or Entrance Length of Developing Flow. The actual development length isn't that important beyond knowing that you have to have a longer region in order to have a fully developed flow, which you can then use for useful stuff. Also, Entrance Length doesn't tell the casual observer that this has anything to do with mechanical engineering or fluid mechanics. any thoughts?  TimeEngineer (talk) 10:49, 16 December 2020 (UTC)


 * The common solution for such articles on Wikipedia would seem to be Article title + technical area in brackets. So that would give Entrance length (fluid dynamics). I was hopeless at this subject, I just refer to rules of thumb in practical applications, so can't be much help with the article otherwise. Wikiwayman (talk) 15:40, 16 December 2020 (UTC)
 * Entrance length was the accepted fluid dynamics engineering term by the mid-20th century, and would appear to still hold that distinction, so it is an appropriate title. However, I would concur with adding the parenthetical fluid dynamics as a preferred title if disambiguation is required for readers without a conventional engineering background. Thewellman (talk) 21:42, 16 December 2020 (UTC)
 * I think this is a reasonable solution TimeEngineer (talk) 21:47, 16 December 2020 (UTC)
 * I just checked Potter & Wiggert and Cengel & Cimbala textbooks. One uses 'entrance length' while the other uses 'entry length'. I think 'entrance length' is the right terminology (compared to 'development length' or whatever) since it is what is in use, and that matters. Hence Entrance length (fluid dynamics) would be good. Jdpipe (talk) 01:54, 17 December 2020 (UTC)

Adjusting entrance length correlation
I noticed that the laminar entrance length correlation is given as L=0.05*Re*D and has a good reference. As estimating the entrance length is not an exact science, this is great, but I think an improved correlation would be L=0.06*Re*D. The first reference in turn references a source from 1942 while the second reference references two sources from 2000 and 2005 respectively which would make the 0.06 coefficient correlation more modern. Also, a cursory internet search of other websites seemed to favor the correlation with a coefficient of 0.06. Similarly for turbulent flow, the same reference by White states that it used to favor the L=4.4*Re^(1/6)*D correlation, but now favors a more modern correlation of L=1.6*Re^(1.4)*D for Re<=10^7. However, I am less familiar with turbulent correlations and other internet sources seem to favor the correlation you show, but might be worth looking into. Thank you. Smithjg4 (talk) 15:06, 22 June 2021 (UTC)

Merger proposal

 * Merge I propose merging Thermal entrance length with Entrance length (fluid dynamics) . I think there's a lot of WP:OVERLAP between the section in this page and Thermal entrance length and this section goes into more detail. As a result, that page isn't necessary (or if it is, it needs to be greatly expanded). Karthanitesh (talk) 00:37, 19 January 2022 (UTC)
 * ✅ Klbrain (talk) 22:14, 25 December 2022 (UTC)