MathGroup Archive 2013

[Date Index] [Thread Index] [Author Index]

Search the Archive

bad PDE solution...


As a first simple test case of a more complicated pb I want to solve the 
plane diffusion equation.
It seems NDSolve gives a bad answer to the simple step case but I can't 
find what's happening...

(* Set up the equation: *)

eq1=D[h[t,x],x,x]- k1 D[h[t,x],t]==0

const=k1-> 10000

(*"solve" it...*)

sol = NDSolve[
    {D[h[t, x], {x, 2}] - k1 D[h[t, x], t] == 0, h[0, x] == 0,
        h[t, 1] == 0, h[t, 0] == 1 - Exp[-10^6*t]} /. const,
    h, {t, 0, 10^-3}, {x, 0, 0.01}][[1]]

right one"]

(* Test the Erfc[x/(2Sqrt[t/k1])] solution *)
Release[Hold[D[h[t,x],x,x]- k1*D[h[t,x],t]]/. 

I hope I'm doing something wrong, but I can find what...


  • Prev by Date: Re: wrong result when computing a definite integral
  • Next by Date: Re: Aligning graphics on frame boundaries
  • Previous by thread: Re: Ask for help: how to let mathematica output Fortran code with fewest
  • Next by thread: Re: bad PDE solution...