Talk:Newtonian fluid

From Wikipedia, the free encyclopedia

WikiProject Physics This article is within the scope of WikiProject Physics, which collaborates on articles related to physics.
??? This article has not yet received a rating on the assessment scale. [FAQ]
??? This article has not yet received an importance rating within physics.

Help with this template Please rate this article, and then leave comments to explain the ratings and/or to identify its strengths and weaknesses.

This article doesn't work at all for me, anymore. I keep getting errors, i.e.: "

A simple equation to describe Newtonian fluid behaviour is

   Failed to parse (Can't write to or create math output directory): \tau=\mu\frac{dv}{dx}


where

   Failed to parse (Can't write to or create math output directory): \tau

" Sim 03:15, 1 September 2006 (UTC)

The article is well and good for those who have done uni-level maths, but makes little sense at all to those who don't... compare non-Newtonian_fluid, which is very clear as to what's going on. --User:Firien § 11:55, 3 February 2006 (UTC)

  • How about now? Should I be removing the template? Sim 01:21, 6 February 2006 (UTC)
    • A colleague and I have done some looking into the subject (ok, a lot of looking into the subject :) and expanded further as just added to the article page. I'm happy to have the template removed, if you think what's down now is good? --User:Firien § 12:02, 6 February 2006 (UTC)

What's with the removal of the delta factor? Here - while I can't parse it completely, I think the component is the shear perpendicular to a given face (i=j) by grad velocity, which looks like a flow factor, which the shear should depend on; flagging it also because it's the only edit by that IP, and I'd like to get it verified before letting it go! --User:Firien § 18:46, 8 February 2006 (UTC)

The current form is fine for i \ne j, but that does need to be noted or replaced with \tau_{ij}=\mu\left(\frac{\partial v_i}{\partial x_j}+\frac{\partial v_j}{\partial x_i} \right)- \left ( p_m + \frac{2}{3}\mu\nabla\cdot\overline{v}\right)\delta_{ij} —kotepho 2006-03-19 22:54Z

The article currently starts with: "A Newtonian fluid (named for Isaac Newton) is a fluid that flows like water". I find this confusing because: 1. it's not clear in what way it's supposed to flow like water, and: 2. water is not a newtonian fluid - for large stress it reacts like a solid (i.e. when an asteroid hits water, it shatters as the hydrogen bonds have no time to realign), and for small stresses there are miniscus forces (so a jesus lizard can walk on water) so the stress/rate of strain curve is not linear and doesn't go through the origin.

Also, it's not clear to me if the 'rate of strain', and the velocity gradiant that appears in the equation are the same thing.

I hope someone who considers himself qualified will rewrite the definition. 88.153.104.131 20:27, 22 July 2007 (UTC)