How to Decouple a System of 3 Coupled Linear PDEs?

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SUMMARY

The discussion focuses on decoupling a system of three coupled linear partial differential equations (PDEs) represented in matrix form. The coefficients α, β, and γ are functions of spatial variables r and θ. The user aims to derive a single second-order equation for the variable ψ by diagonalizing the matrix operator. If decoupling proves unfeasible, the user seeks references for solving the system using finite difference methods, specifically mentioning familiarity with first-order systems and the method of characteristics.

PREREQUISITES
  • Understanding of linear partial differential equations (PDEs)
  • Familiarity with matrix operations and diagonalization
  • Knowledge of finite difference methods for numerical solutions
  • Experience with the method of characteristics for first-order systems
NEXT STEPS
  • Research techniques for diagonalizing matrices in the context of PDEs
  • Study finite difference methods specifically for coupled PDE systems
  • Explore the method of characteristics in greater depth for solving first-order PDEs
  • Investigate literature on decoupling methods for linear PDE systems
USEFUL FOR

Mathematicians, physicists, and engineers working with coupled linear PDEs, as well as researchers seeking numerical methods for solving complex systems of equations.

vibe3
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Hi all, I have a system of 3 coupled linear PDEs which can be expressed in matrix form as:

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

where the coefficients \alpha,\beta,\gamma are functions of position r,\theta.

I believe its possible to decouple this system and end up with a single, 2nd order equation for \psi, 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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This is a first order system, I would recommend method of characteristics.
 

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