  We discuss exterior and classical interior alternatives for evaluating fluid
flow induced forces on bodies. The discussion aims at a reduction of the total
shape derivative, achieved through a decoupling of control and objective in the
exterior approach. In this case, geometric as well as convective contributions
to the shape derivative vanish. Convective contributions depend on primal
physics and may disappear, which is not the case for geometric components. The
latter can be interpreted as curvatures immanent to industrial applications.
The remaining local derivative of the objective functional can be determined
efficiently with an adjoint system, that differs to the classical approach in
its boundary conditions only and resembles an ALE strategy. A two-dimensional
flow exposed to gravity illustrates the features of the exterior approach,
whereby carefully derived derivatives from a second order Finite-Difference
study were used to validate the results.
