Solution for a nonlinear PDE

In summary, the conversation revolves around the existence conditions and numerical solutions of a general dynamic system described by the equation dXi/dt = Fi(X1, X2,...,Xn), i=1,...,n. The first question relates to the existence conditions of two PDEs with different inner products and boundary conditions. The second question asks about the numerical solution of the system, with the person mentioning their attempt at using a matrix format and Newton method but struggling with convergence. The conversation ends with a request for any ideas or comments on finding a general convergence scheme.
  • #1
sunon77
2
0
For a general dynamic system: dXi/dt = Fi(X1, X2,...,Xn), i=1,...,n,
Q.1
do you have some ideas of the existence conditions of following PDE:
a) (grad U, grad U + F) = 0 in n-dimension domain, (,) is inner product;
b) U >=0

Does it need a first type or second type of boundary condition?

Q.2
If solution does exist, how to solve it numerically?
- I tried to write in differential equation in matrix format, then apply Newton method. It is very difficult to have a converge scheme.

A more detailed simple example is attached to explain the solution that I tried.

Many thanks for your ideas or comments
 

Attachments

  • NonlinearODEProblem.doc
    121 KB · Views: 217
Last edited:
Physics news on Phys.org
  • #2
I despair of finding a general convergence scheme as convergence is very sensitive to the nature of Fi's.
 

1. What is a nonlinear PDE?

A nonlinear PDE, or partial differential equation, is an equation that involves multiple variables and their partial derivatives. Unlike linear PDEs, which can be solved using simple algebraic methods, nonlinear PDEs require more complex techniques and often have multiple solutions.

2. Why are nonlinear PDEs important?

Nonlinear PDEs are an essential tool in modeling and understanding complex physical phenomena, such as fluid dynamics, heat transfer, and quantum mechanics. They also have applications in engineering, finance, and other fields.

3. How do you solve a nonlinear PDE?

Solving a nonlinear PDE involves finding a function or set of functions that satisfy the given equation. This can be done through various techniques, such as separation of variables, the method of characteristics, or numerical methods like finite difference or finite element methods.

4. What challenges are involved in solving a nonlinear PDE?

Nonlinear PDEs can be very challenging to solve due to their complex nature and the lack of general solution methods. The presence of multiple unknown functions and their derivatives makes it difficult to find exact solutions, and numerical methods often require significant computational resources.

5. Are there any real-world applications of nonlinear PDEs?

Yes, nonlinear PDEs have numerous real-world applications, such as predicting weather patterns, designing aircraft wings, simulating traffic flow, and modeling chemical reactions. They are also used in image and signal processing, medical imaging, and many other fields.

Similar threads

Replies
4
Views
1K
  • Differential Equations
Replies
2
Views
2K
  • Differential Equations
Replies
1
Views
1K
  • Differential Equations
Replies
13
Views
2K
  • Differential Equations
Replies
5
Views
2K
  • Differential Equations
Replies
2
Views
1K
Replies
1
Views
1K
  • Math POTW for Graduate Students
Replies
3
Views
749
Replies
4
Views
1K
  • Math POTW for University Students
Replies
1
Views
434
Back
Top