Abstract: Considering that the local consistent mending technique destroys the original model topology and increases the number of surface patches needed for freeform surface shape modeling, a topology recovery approach dealing with complex trimmed confluent surface model based on local consistent fitting is proposed. The N-patch corner of topology recovery model is relocated and the complete curvilinear grid is constructed, which determines the topology, geometrical shape and boundary of recovery N-sided confluent surface model. The freeform surface approximation technique is utilized to approach point cloud sampled from trimmed confluent surface and consistent surface to reconstruct B-spline surface in order to recover the topology of trimmed confluent surface. The multiple recovery surfaces approximated to point cloud subject to tight tolerance are beautified globally, which generates convergent G1 continuity between adjacent B-spline surfaces and smoothly stitches the N-patch corner. Practical application shows that the presented topology recovery technique not only recovers the topological and geometrical properties of original confluent surface model, but also achieves global G1 continuity.

Key words: Characteristic curve, Curvilinear grid, Freeform surface, Reverse engineering, Surface approximation, Topology recovery, lubrication, numerical optimization, Reynolds equation, herringbone groove bearing