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Physical meaning for Sin(x^2)

  • 16-03-2011 8:55am
    #1
    Mr Marri
    Closed Accounts Posts: 266 ✭✭


    Hi Folks,

    I'm looking at some experimental test results for a flow field and have accidently discovered that these results are an extremely good match for Constant*Sin(x^2).
    Is there any phisical meaning of sin(x^2) or is there any other ways that sin(x^2) can occur ie is there any trig idenities that would give me Sin(x^2).
    I have tried other possible function such as EXP and while I can get a polynomal fit with y = 5E-05x2 - 0.0478x + 13.687 it is not as good as Constant*Sin(x^2).

    Thanks in advance as I'm really stumped by this.


Comments

  • #2
    ZorbaTehZ
    Registered Users, Registered Users 2 Posts: 2,149 ✭✭✭ZorbaTehZ


    It appears in the formula for Fresnel diffraction, otherwise I can't say much.


  • #3
    Fremen
    Registered Users, Registered Users 2 Posts: 2,481 ✭✭✭Fremen


    You probably need to tell us a bit more about the experiment if you want any help - for instance, what's causing the sinusioudal behaviour of your data in the first place?


  • #4
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 93,563 Mod ✭✭✭✭Capt'n Midnight


    don't forget that at small angles sin(x) is a close approximation to x ;)

    what the Reynolds number / turbulent flow ?


  • #5
    Mr Marri
    Closed Accounts Posts: 266 ✭✭Mr Marri


    Test results are for a propeller, So I was expecting the lift dependant drag to be a funtion of angle (sin), but got this instead, to be honest I'm tempted to ignore it as I can't think of any way Sin(x^2) can be produced.

    Yes i thought I might get away with sin of a small angle but unfortunately that does not give a good match. :-( as the angles are up to 20 deg.

    I think it must be a combination of Sin and Exponental, I'll strip out the sin and see what it looks like.

    Thanks Folks


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