|WikiProject Physics / Fluid Dynamics||(Rated Start-class, Mid-importance)|
- But now significant longer than this one, that is some useless trivia, too ;-). Cheers, 22.214.171.124 06:33, 8 September 2006 (UTC)
I remember that there is a formula for the frequency of oscillation of a drop of non-viscous liquid close to sphericity, under the influence of the surface tension. But I don't remember the formula. Can someone put it on the page? At least for the first mode of vibration. Better still if there is a formula for other modes. (I have searched for such a formula on the Polish page - all I managed to grasp is that a drop is a kropla!) David Olivier 00:23, 11 September 2006 (UTC)
If droplet redirects to drop, is it good practice to use drop in other articles?Trialex 05:26, 16 October 2006 (UTC)
The drops from a dripping tap do not drip with a constant frequency. In fact it is a chaotic phenomenon. The animation suggests the regular viewpoint instead. Not sure how to fix the animation itself. Maybe a simple note would be good enough. --MarSch 10:56, 29 October 2006 (UTC)
- Not exactly constant, but close. Do you have a reference? — Omegatron 05:26, 6 December 2006 (UTC)
Drop size formula
I think it's almost certain that the equation linking drop size to surface tension is wrong. The factor was changed from 2 to 3 without explanation in the 09:16, 8 February 2006 edit.
I think that the factor should be changed back to 2, and the contact angle in the diagram should be measured at the place where the drop forms, not at a second meniscus in the tube. With these two modifications, the equation then represents a correct force balance between the weight of the drop and the surface tension, assuming that the flow rate is zero and that the pressure at the tube opening (just above the drop) is the same as atmospheric pressure. I can't find any references for this though: the standard way of measuring surface tension from a pendant drop seems to be the method of Harkins and Brown (Harkins, W.D, Brown, F.E, J. Amer. Chem. Soc. 41, 499 (1919)) which does not involve the contact angle explicitly, but instead relies on a drop shape correction factor that is linked to it. Chrisjohnson (talk) 02:47, 18 July 2008 (UTC)
- I've modified the diagram, updated the article and included a few of the references I used. While the final formula didn't come from any particular reference, the derivation is trivial based on the source material. LightYear (talk) 04:36, 5 November 2008 (UTC)
Average tap water drop volume
But add the tension gas liquid whit the cosine and the tension liquid solid whit no cosine (liquid solid perpendicular to g) is not a bit more correct? —Preceding unsigned comment added by 126.96.36.199 (talk) 02:10, 19 August 2008 (UTC)
pendant drop test
According to Adamson, A.W., Physical Chemistry of Surfaces (5th ed., 1990), the pendant drop test is different (p.28-30), and the mentioned test is the drop weight method (p.21-23). effeietsanders 22:54, 26 November 2009 (UTC)
"The shape of a drop falling through a gas is actually more or less spherical for drops less than 2mm in diameter."
Isn't that for water falling through air? I'd assume a different size is relevant to lead falling through hydrogen (or lead falling in a shot tower to produce balls of shot larger than 2mm). (talk) 19:50, 28 May 2016 (UTC)