Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Longitudinal strain rate derivation

  1. Jun 8, 2014 #1
    Hi,

    The attachment below is about strain rate in fluids*. It shows how the strain rate [tex]d\phi/dt[/tex] is related to the velocity field derivative [tex]du/dx[/tex] when you stretch the element in x (i.e. longitudinal strain).

    It has no intermediate steps, and I can't see how the angle has been related to the velocity field (or where the 0.5 factor comes from).

    Thanks very much.

    *From website: http://www.see.ed.ac.uk/~johnc/teaching/fluidmechanics4/2003-04/fluids5/stress.html [Broken]

    Sorry about the small picture - that's how it is on the website.
     

    Attached Files:

    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Jun 9, 2014 #2
    I would assume there's a simple trigonometric identity to apply. What makes this difficult for me is that phi is present in both the x and y directions, whilst the equation somehow describes it through the x-axis.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook




Loading...