ABSTRACT
CAD geometries are most often exchanged between analysis tools using NURBS patches to represent the boundary (BRep). We present a method where the control points of the BRep are used to automatically derive parametrisations suitable for shape optimisation with gradient-based methods. Particular focus is on ensuring geometric continuity between the NURBS patches through formulation of discrete constraints. Design variables then arise from an orthogonal basis to the remaining design space using a singular value decomposition (SVD). The manuscript presents the extension of earlier work on B-spline surfaces to full NURBS surfaces and investigates the effect of the SVD cut-off on the optimisation results. An estimation of the effective rank is proposed which allows to automatically determine a suitable cut-off value. The effectiveness of the algorithm is demonstrated for the minimisation of total pressure loss over a section of an automotive climate duct, and a U-bend cooling channel.
Disclosure statement
No potential conflict of interest was reported by the authors.