A major bottleneck for application of gradient-based optimisation in industrial design chains is the parametrisation of the shape. This novel approach keeps the CAD description in the design loop by modifying the control points of the NURBS patches of the surface description. As a unique feature this algorithm maintains continuity between patch interfaces, which is essential for industrial application and generic CAD geometries, an aspect that has not been tackled in the literature so far.

The NURBS description guarantees a smooth shape, the algorithm maintains continuity between patch interfaces, which is essential for industrial application and generic CAD geometries. The figure shows initial and final shape and contours of velocity magnitude for an industrial air duct when minimising the pressure drop. The approach produces significant deformations, the streak-like deformation suppresses separation and secondary flow.