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# Homogeneous Dirichlet

Homogeneous Dirichlet conditions force the wavefield to be zero at the specified boundary.

In the scalar acoustic case, this simply gives

$\phi = 0,\quad\text{on~}\Gamma,$

and in elastic media, we obtain

$u = 0,\quad\text{on~}\Gamma.$

It is possible to fix only certain components of the displacement field $u$ in the elastic case.