Talk:Rayleigh–Taylor instability

message: What the *** is tangential gravity??? 80.177.213.144 19:05, 19 Apr 2005 (UTC)
thread_title:  Old discussions 

message: The first place I ever heard of R-T instability (called just "Taylor Instability" at the time) was in the subject of nuclear weapons design.  R-T occurs in the pit when the implosion shockwave crosses the border between two components, most notibily the uranium tamper and berylium reflector.  Future re-writes of this article might reflect this.  Reference: ()
Also: Who were Rayleigh and Taylor. Is that the same Ted Taylor, the nuclear weapons designer.
Lord Rayleigh aka J. W.  Strutt, and (Sir) Geoffrey Ingram Taylor - Taylor worked for UK MoD for  a time and developed the 'shaped charge' where the metal cone flows like a fluid and forms an armour-piercing jet - he also worked on the Manhattan Project - HTH Linuxlad 08:50, 27 July 2006 (UTC)
thread_title:  Nuclear Weapons R-T 

message: Note that the RT instability is not to be confused with the Rayleigh instability (or Plateau-Rayleigh instability) of a liquid jet. This latter instability, sometime called the hosepipe (or firehose) instability, occurs due to surface tension, which acts to break a cylindrical jet into a stream of droplets having the same volume but lower surface area. This reference: Actual images and videos of RT fingers ends with "Manifestations of Rayleigh-Taylor instability," which actually illustrates Plateau-Rayleigh instability. Something's gotta give. -AndromedaRoach 03:19, 17 December 2006 (UTC)
thread_title:  Inaccuracy in reference 

message: http://arxiv.org/abs/physics/0610082
According to secion 5 of the reference, (see page 9), some "Rayleigh theorem" is incorrect.
I don't know of this is the place for that, but there can't be too
many Rayleigh's in the field of Fluid Dynamics, so they are probably talking about the same man, even if it isn't quite the same instability. Crysta1c1ear 03:28, 8 January 2007 (UTC)
thread_title:  Rayleigh Theorem is incorrect 

message: I added a reference to Chandrasekhar's book and removed the 'need citations' tag from the linear stability section.  I hope this is a sufficient reference.  I think this is standard wikipedia policy for mathematical articles, since this entire section is self-verifiable in the sense that it's a mathematical theorem.  Otherwise it would be cumbresome to add a reference at the end of every line where a mathematical statement is made.Onaraighl (talk) 16:39, 28 June 2008 (UTC)
thread_title:  Citations 

message: I studied physics as an undergraduate not too horribly long ago, and I can't make heads or tails of the third paragraph in the introduction to this page.  It seems like we're jumping into some very technical stuff without providing some sort of introduction to it or even linking to the relevant pages. Cww (talk) 04:39, 5 May 2009 (UTC)
thread_title:  Laymans' terms 

message: Just an idea: It might be useful to include some mention of a lava lamp in this article, as a real-life example of an unstable fluid mechanical system.  I'm not sure how appropriate an example it would be, though.  Perhaps someone more expert in fluid mechanics would have a better opinion.  CosineKitty (talk) 20:36, 10 August 2011 (UTC)
thread_title:  Lava Lamp 

message: The curl of an irrotational velocity field (i.e., \nabla\times\textbf{u}'=0), which is also solenoidal (i.e., \nabla\cdot\textbf{u}'=0) does not, in general, satisfy \nabla^2\psi=0, where \psi is the stream function satisfying \textbf{u}'=\nabla \times\psi. In general, \nabla\times(\nabla \times\psi) =\nabla(\nabla\cdot\psi)-\nabla^2\psi. On the other hand, for an irrotational and solenoidal vector field, the velocity potential (\varphi) can be shown to satisfy Laplace's equation, \nabla^2\varphi=0. What other assumptions were made in the actual derivation such that \nabla^2\psi=0, assuming this is correct? – Roche398 (talk) 16:19, 6 July 2013 (UTC)
replies: text: Old post, but that use of the stream function \psi is fine. Perhaps the only missing statement is that the flow is considered two-dimensional. Perhaps this is the additional assumption you were after. Otherwise, your objection seems to take \psi as a vector field; it is in fact (canonically) a scalar field, so your use of the vector Laplacian, \nabla\times(\nabla \times\psi) =\nabla(\nabla\cdot\psi)-\nabla^2\psi, is not meaningful (i.e. on the RHS there both divergence and curl shows up, which is not meaningful if operating on a scalar field.) In truth there are formulations of it where it is a vector potential, but the end result comes to the same thing. The existence of a (scalar field) stream function satisfying \nabla^2\psi=0 follows at once from a two-dimensional irrotational and solenoidal velocity field: the (2d) solenoidal property allows that the scalar field exists (via continuity), and the irrotational property allows that same scalar field to satisfy Laplace's equation. Osmanthus22 (talk) 14:40, 13 December 2017 (UTC)
thread_title:  Details of linear stability analysis are incorrect 

message: "This instability, sometimes called the hosepipe (or firehose) instability, occurs due to surface tension, which acts to break a cylindrical jet into a stream of droplets having the same volume but lower surface area." When an object is broken into multiple pieces, they usually have greater surface area than the original object. WilliamSommerwerck (talk) 23:18, 3 May 2014 (UTC)
thread_title: non-sequitur?

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thread_title:  External links modified (January 2018)