  Engineering design via CAD software relies on Non-Uniform Rational B-Splines
(NURBS) as a means for representing and communicating geometry. Therefore, in
general, a NURBS description of a given design can be considered the exact
description. The development of isogeometric methods has made the geometry
available to analysis methods Hughes et al. (2005). Isogeometric analysis has
been particularly successful in structural analysis; one reason being the
wide-spread use of two-dimensional finite elements in this field. For fluid
dynamics, where three-dimensional analysis is usually indispensable,
isogeometric methods are more complicated, yet of course not impossible, to
apply in a general fashion. This paper describes a method that enables the
solution of fluid-structure interaction with a matching spline description of
the interface. On the structural side, the spline is used in an isogeometric
setting. On the fluid side, the same spline is used in the framework of a
NURBS-enhanced finite element method (extension of Sevilla et al. (2011)). The
coupling of the structural and the fluid solution is greatly facilitated by the
common spline interface. The use of the identical spline representation for
both sides permits a direct transfer of the necessary quantities, all the while
still allowing an adjusted, individual refinement level for both sides.
