How to find eigenvalues of a linear operator consists of laplacian?

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I have the following matrix of linear operator consists of Laplacian \begin{bmatrix}0&1&0\\\Delta&\Delta& 0\\0&0&\Delta\end{bmatrix} acting on \begin{bmatrix}w\\w_t\\u\end{bmatrix}, where $u=u(t,x)$ is the velocity of fluid/heat , $w(t,x)$ is the structural displacement. So it is a fluid-structure interaction problem, where $u=0$ on fluid boundary, and $u=w_t $ on structure boundary. How could I find eigenvalues of it? How to use Mathematica/Matlab to get eigenvalues?