Talk:Froude number

Hi

I reckon this page might be better split into two: Froude number and a separate page for densimetric Froude number. Comments?

(William M. Connolley 09:31, 2004 Mar 16 (UTC)) Its a fairly short page now and if split would be very short. It might be better to expand it first. Unless you want to create links into it. But if you feel strongly, go ahead.

Fr and Ri are interchanged here
The definitions of Froude number and Richardson number are interchanged. Should I edit it or suggest that the author should do so? I'm not sure of the protocal. --Dankelley 01:04, 19 Jul 2004 (UTC)

Hi Dankelly.

The usual protocol would be for you to edit the article, if you are sure of your position. However, in this case, it would be better to do one of the following:


 * 1) leave the articles unchanged because the definitions are generally accepted
 * 2) say something like "Some workers (such as X and Y) follow the notation used in books Y and Z, and seminal articles  A and B, and use a different set of definitions, viz:  . ..

I'd do the second option myself If I'd ever seen Fr and Ri defined the other way round!

Best wishes

Robinh 08:16, 19 Jul 2004 (UTC)


 * (William M. Connolley 21:16, 24 Jul 2004 (UTC)) The defs look OK to me (in the sense that they match googling, eg: http://scienceworld.wolfram.com/physics/RichardsonNumber.html or http://www.gfdl.noaa.gov/~smg/MOM/web/guide_parent/s7node262.html


 * And just to be sure I've looked it up in Gill who agrees F = U / N_1.H

William Froude takes credit for the Froude number which bears his name. It was originally defined by Froude in his 'Law of Comparison' in 1868 in dimensional terms as Speed-Length ratio

Speed-Length Ratio = V / ( L )^0.5

where:


 * v = speed in knots
 * L = LWL in feet

The Naval Constructor Reech put forward the concept in 1832 but had not demonstrated how it could be applied to practical problems in ship resistance.

Fn was later refined to the non-dimensional :

Fn = v / ( g L )^0.5

where:


 * v = speed in m/s
 * g = gravity in m/s2
 * L = LWL in m

It should be defined as such.

Ref: Principles of Naval Architecture (SNAME), 1988, Vol II, Page 5.

Jmvolc 00:42, 19 May 2006 (UTC)

Length and Depth Froude numbers
This document explains Length and Depth Froude numbers, and appears relevant to development of the article.

http://www.qub.ac.uk/waves/fastferry/reference/MCA457.pdf

I have added an external link to it from the article. GilesW 13:26, 25 June 2007 (UTC)

Wavemaking resistance for planing boats
The wavemaking resistance increases near the critical Froude number, but above it drops significantly. Which is why planing is a desired condition for, for instance, small sail-boats. -- Crowsnest (talk) 21:31, 9 April 2009 (UTC)

Froude's Law
I can't decide whether to add a section on Froude's Law here or create a new (small) page. Perhaps a more experienced Wikipedian will know what to do. Here is a start on the content:

Froude's law states that the velocity of a water-born creature or craft is proportional to the square root of it length.

Reference: Thompson, D W., 1992. On Growth and Form. Dover reprint of 1942 2nd ed. (1st ed., 1917). ISBN 0-486-67135-6, p. 31.

Links: http://froude.sdsu.edu/ and http://www.sjsu.edu/faculty/watkins/froude.htm

Cjfsyntropy (talk) 03:54, 17 December 2009 (UTC)

Merge proposal
Suggest merging two pages - Froude resistance curve has almost no content, and no references. Weakopedia (talk) 08:02, 30 June 2010 (UTC)

i second the motion of putting Froude's acomplishments together

reading Gregor Tarjan on catamarans i learn Froude (same William?) also did pendulem expiriments prooving no mather how inclined the wave angle, the pendulum remains perpendicular to the sea due to the momentum effect, logic, but there is more to it and very little to find —Preceding unsigned comment added by 213.46.146.112 (talk) 14:00, 14 August 2010 (UTC)

Link to "gravitational acceleration" goes to "gravitational constant" in error — Preceding unsigned comment added by 174.74.28.25 (talk) 22:30, 12 August 2013 (UTC)

Wave-Line Theory
I'm wondering about attributing Wave-Line Theory to Froude. I refer to a recent article in Physics Today (July 2017) that talks about John Scott Russell developing the theory, starting from work begun in 1835. Froude's work apparently went a long way to discrediting Wave-Line Theory, in part based on testing done with the Raven and Swan models shown in the article. — Preceding unsigned comment added by Normd (talk • contribs) 14:34, 30 July 2017 (UTC)
 * As long as that Physics Today article backs up all the info that ends up in the article, I don't see why not. WP:BOLD and all that. DanHobley (talk) 09:07, 31 July 2017 (UTC)

Bogus statement?
If this was true:-

Dynamics of vessels that have the same Froude number are easily compared as they produce a similar wake, even if their size or geometry are otherwise different.

All ship geometries would be rectangular. — Preceding unsigned comment added by 110.143.72.26 (talk) 13:29, 8 July 2020 (UTC)

This all seems wrong
He towed planks of assorted lengths, painted differently, back in 1860 - to arrive at **FRICTION** formulas. This entire article seems to be talking about drag and other aspects which are not the same thing. — Preceding unsigned comment added by 110.143.72.26 (talk) 13:34, 8 July 2020 (UTC)