MHB Apply Fourier Transform to Solve t2u_t-u_x=g(x)

Click For Summary
SUMMARY

The discussion focuses on applying the Fourier transform to solve the partial differential equation \( t^2u_t - u_x = g(x) \) with the boundary condition \( u(x,1) = 0 \). The correct approach involves taking the Fourier transform with respect to \( x \), treating \( t \) as a constant, leading to the equation \( t^2 \frac{\partial U}{\partial t} - iwU = F(g) \), where \( U(\omega, t) \) represents the Fourier transform of \( u(x,t) \). The next step is to solve this ordinary differential equation (ODE) for \( U \).

PREREQUISITES
  • Understanding of Fourier transforms, specifically in the context of partial differential equations.
  • Familiarity with the notation and operations involving \( u_t \) and \( u_x \).
  • Knowledge of solving ordinary differential equations (ODEs).
  • Basic concepts of boundary conditions in differential equations.
NEXT STEPS
  • Study the properties of Fourier transforms in solving PDEs.
  • Learn how to differentiate under the integral sign in the context of Fourier transforms.
  • Explore methods for solving ordinary differential equations, particularly those involving variable coefficients.
  • Investigate particular solutions for non-homogeneous ODEs.
USEFUL FOR

Mathematicians, physicists, and engineers working with partial differential equations, particularly those interested in applying Fourier analysis to solve complex problems.

Markov2
Messages
149
Reaction score
0
I need to apply Fourier transform to solve the following: $t^2u_t-u_x=g(x),$ $x\in\mathbb R,$ $t>0$ and $u(x,1)=0,$ $x\in\mathbb R.$
How do I apply the Fourier transform for $t^2u_t$ ?

Thanks!
 
Physics news on Phys.org
インテグラルキラー;437 said:
I need to apply Fourier transform to solve the following: $t^2u_t-u_x=g(x),$ $x\in\mathbb R,$ $t>0$ and $u(x,1)=0,$ $x\in\mathbb R.$
How do I apply the Fourier transform for $t^2u_t$ ?

Thanks!

Take the Fourier transform with respect to $x$ then you simply treat $t$ as a constant.

$$ \int \limits_{-\infty}^{\infty} t^2 \frac{\partial u}{\partial t} e^{-i\omega x} dx = t^2 \frac{\partial }{\partial t}\int \limits_{-\infty}^{\infty} u(x,t) e^{-i\omega x} dx = t^2 \frac{\partial U}{\partial t}$$

Here we differenciated under the integral sign, and $U(\omega , t)$ is the notation for the Fourier transform of $u(x,t)$ with respect to $x$.
 
Ah, then I have ${{t}^{2}}\dfrac{\partial U}{\partial t}-iwU=F(g)$ and I need to solve that ODE, first I need a particular solution.

Does this look right?
 
Last edited:
Can anyone confirm this please?
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 12 ·
Replies
12
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 11 ·
Replies
11
Views
5K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 11 ·
Replies
11
Views
3K