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

A Solving two simultaneous integro-differential equations

  1. Oct 13, 2016 #1
    I am trying to find a closed-form (analytical) solution for the two following simultaneous integro-differential equations :

    du[x]/dx= - a v[x] +b ∫〖[1-(y-x)^4 〗].(v[y]-v[x])dy
    (dv[x])/dx= - f u[x] -g ∫〖[1-(y-x)^4 〗].u[y]dy
    With the initial conditions:
    v[0]=e and u[1]=0
    a,b,f,g and e are positive constants
    Both integrals are from y=0 to y=1.
    The unknowns are u[x] and v[x].
  2. jcsd
  3. Oct 13, 2016 #2

    Dr Transport

    User Avatar
    Science Advisor
    Gold Member

    an analytical expression for that set of equations is most likely not going to be found.
  4. Oct 21, 2016 #3
    Just wrote down the start to a solution.
    Differentiate one of the equations with respect to x. You already have expressions for du/dx and dv/dx, so when you differentiate you can substitute the other equation in. Voila! Suddenly you've got an integro-differential equation for only one function. I'll leave you to do the rest of it ;)
  5. Oct 27, 2016 #4
    I thank both friends for their kind help. Fortunately, and after some modifications in the equations, a solution was possible using the numerical solution of two simultaneous differential equations in two variables and one single independent variable. This was done using the NDSolve command within a Mathematica 11 code.
    Thanks again.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted