1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Significance of Perfect Fluid

  1. Jul 10, 2015 #1
    So the textbook I am reading says that a perfect fluid cannot sustain shear stress, or that [tex] p_{yx}=2\mu \dot \epsilon_{yx} =0[/tex], where [itex] \mu [/itex] is the viscosity, and [itex] \dot \epsilon_{yx} [/itex] is the rate of angular deformation. Then it says when [itex] \dot \epsilon_{yx} =0[/itex], this means that "two adjacent horizontal layers of a perfect fluid can move at different velocities without one layer affecting the other layer through internal resistive stresses." This seems to me, however, like what would happen if the viscosity were zero.

    Can someone clear up my misconception?
  2. jcsd
  3. Jul 10, 2015 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member
    2017 Award

    Viscosity is zero in a perfect fluid. The situation described is not ##\dot\epsilon_{xy}=0## but ##\neq 0##.

    Edit: Why is \eps not a standard TeX command yet???? :headbang:
  4. Jul 10, 2015 #3
    I think ideal fluids are a subset of perfect fluids, at least according to my book.

    Attached Files:

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook