Solution
= Solution
The <irrotational flow> has a <velocity potential> $\phi$ with $(u,w)=(\phi_x,\phi_z)$. The <incompressible flow> satisfies $u_x+w_z=0$, hence the interior <Laplace equation> is
$$
\boxed{\phi_{xx}+\phi_{zz}=0,\qquad -h<z<\eta(x,t)}.
$$
The <ice> supplies a boundary load through its <bending stiffness>; it does not alter this interior consequence of <mass conservation>.