First order linear non-homogeneous PDE

Click For Summary

Homework Help Overview

The discussion revolves around finding the general solution to a first order linear non-homogeneous partial differential equation (PDE) given by y²(ux) + x²(uy) = 2y², along with an initial condition. Participants are exploring methods to derive a particular solution to the PDE.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to solve the associated homogeneous equation and identifies the characteristic equation. They express uncertainty about finding a particular solution to the non-homogeneous PDE and inquire about systematic methods for doing so.
  • Some participants suggest specific forms for the solution, such as considering ux = 2 and uy = 0, and propose u = 2x as a potential particular solution. Others question the existence of a more general method applicable to complex cases.

Discussion Status

Contextual Notes

Participants are navigating the complexities of first order linear non-homogeneous PDEs and are considering the implications of the initial condition provided in the problem statement.

kingwinner
Messages
1,266
Reaction score
0

Homework Statement


Find the general solution to the PDE and solve the initial value problem:
y2 (ux) + x2 (uy) = 2 y2, initial condition u(x, y) = -2y on y3 = x3 - 2


2. Homework Equations /concepts
First order linear non-homogeneous PDEs


The Attempt at a Solution


I know that the general solution to the non-homogeneous PDE = a particular soltuion to it + the general solution to the assoicated homogenous PDE, so I first consider to assocatied homogeneous equation:
y2 (ux) + x2 (uy) = 0

The characteristic equation is dy/dx = x2/y2
And the solution to this ODE is y3 - x3 = C where C is an arbitrary constant.
So the general solution to the homogeneous equation is u = f(y3 - x3) where f is arbitrary differentiable function of one variable.
But then I am stuck. How can I find a particular solution to the original non-homogeneous PDE? Is there a systematic way to find one such solution?

Any help is appreciated! :)
 
Physics news on Phys.org
Can someone please help? I am still stuck on this problem... :(
 
kingwinner said:
Find the general solution to the PDE...
y2 (ux) + x2 (uy) = 2 y2
...

How can I find a particular solution to the original non-homogeneous PDE? Is there a systematic way to find one such solution?

Any help is appreciated! :)

I don't know about any systematic ways, but just looking at it, if you could find a u such that ux = 2 and uy = 0 that would do it. And that's easy.
 
LCKurtz said:
I don't know about any systematic ways, but just looking at it, if you could find a u such that ux = 2 and uy = 0 that would do it. And that's easy.
Then, I think u=2x will work as a particular solution.

But really, can anyone suggest a more general/systematic way to solve it that would work also for more complicated first order linear PDEs?

Thanks!
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
1K
Replies
2
Views
2K
  • · Replies 36 ·
2
Replies
36
Views
6K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 12 ·
Replies
12
Views
3K
  • · Replies 11 ·
Replies
11
Views
2K
Replies
2
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K