Splitting PDE into system of PDEs

[nkinar]

Hello:

I am wondering if there is a general way of splitting the following PDE into two separate equations. I would like to re-write the second-order spatial derivatives on the LHS as first-order derivatives.

<br /> \[<br /> \frac{{\partial p^2 }}{{\partial x^2 }} + \frac{{\partial p^2 }}{{\partial y^2 }} = A\frac{{\partial ^2 p}}{{\partial t^2 }} + B\frac{{\partial p}}{{\partial t}}<br /> \]<br />

So once the above equation is split, there should be two equations involving only first-order spatial derivatives (\partial p/\partial x and \partial p/\partial y).

 

[nkinar]

I think that this equation can be split using the following rules:

(1) The LHS of the wave equation is split by introducing another variable and removing a del operator.

<br /> \[<br /> \frac{{\partial \psi }}{{\partial t}} = \nabla p<br /> \]<br />(2) The RHS of the wave equation is split by removing a derivative:

<br /> \[<br /> \nabla \psi = A\frac{{\partial p}}{{\partial t}} + Bp<br /> \]<br />