Coupled linear PDE system

In summary, the conversation discusses a system of 3 coupled linear partial differential equations expressed in matrix form, with coefficients that are functions of r and \theta. The goal is to decouple the system and obtain a single, 2nd order equation for \psi, potentially through diagonalization of the matrix operator. If this is not feasible, the speaker is seeking references for solving the system using finite difference methods. The suggestion is to use the method of characteristics since this is a first order system.
  • #1
vibe3
46
1
Hi all, I have a system of 3 coupled linear PDEs which can be expressed in matrix form as:

[tex]
\left(
\begin{array}{ccc}
\alpha_1 \partial_{\theta} & \alpha_2 & \alpha_3 \\
\beta_1 \partial_r & \beta_2 & \beta_3 \\
0 & \gamma_2 \partial_{\theta} & 1 + \gamma_3 \partial_r \\
\end{array}
\right)
\left(
\begin{array}{c}
\psi \\
E_r \\
E_{\theta}
\end{array}
\right)
=
\left(
\begin{array}{c}
-\alpha_4 \\
-\beta_4 \\
0 \\
\end{array}
\right)
[/tex]

where the coefficients [itex] \alpha,\beta,\gamma [/itex] are functions of position [itex]r,\theta[/itex].

I believe its possible to decouple this system and end up with a single, 2nd order equation for [itex]\psi[/itex], but I don't know how to proceed to do this. Somehow it must be possible to diagonalize the matrix operator.

If its not possible, then does anyone know of any references for solving such a system with finite difference methods? I'm familiar with FD methods for a single equation but haven't done coupled equations before.
 
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  • #2
This is a first order system, I would recommend method of characteristics.
 

What is a coupled linear PDE system?

A coupled linear PDE system is a set of partial differential equations (PDEs) that are interconnected and dependent on each other. This means that the solutions to one equation will affect the solutions to the other equations, making them "coupled". Linear PDEs involve the partial derivatives of dependent variables that are proportional to the dependent variables themselves.

What are some common examples of coupled linear PDE systems?

Some common examples of coupled linear PDE systems include the Navier-Stokes equations, the Maxwell equations, and the equations of elasticity. These systems arise in various fields of science and engineering, such as fluid dynamics, electromagnetism, and structural mechanics.

What methods can be used to solve coupled linear PDE systems?

There are several methods that can be used to solve coupled linear PDE systems, including separation of variables, the method of characteristics, and numerical methods such as finite difference or finite element methods. The choice of method depends on the specific equations and boundary conditions of the system.

What are some challenges in solving coupled linear PDE systems?

One of the main challenges in solving coupled linear PDE systems is the complexity of the equations and their interdependence. This can make it difficult to find analytical solutions, and numerical methods can be computationally intensive. Another challenge is ensuring the accuracy and stability of the solutions, especially for time-dependent systems.

How are coupled linear PDE systems used in scientific research?

Coupled linear PDE systems are used in scientific research to model and understand various physical phenomena, such as fluid flow, heat transfer, and electromagnetic fields. They are also used in engineering applications to design and optimize systems, such as aircraft wings, electronic circuits, and structural components.

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