  This paper presents a novel variational formulation to simulate linear
free-surface flow. The variational formulation is suitable for higher-order
finite elements and higher-order and higher-continuity shape functions as
employed in Isogeometric Analysis (IGA).
  The novel formulation combines the interior and free-surface problems in one
monolithic formulation. This leads to exact energy conservation and superior
performance in terms of accuracy when compared to a traditional segregated
formulation. This is confirmed by the numerical computation of traveling waves
in a periodic domain and a three-dimensional sloshing problem. The isogeometric
approach shows significant improved performance compared to traditional finite
elements. Even on very coarse quadratic NURBS meshes the dispersion error is
virtually absent.
