The role of Bézier extraction in adaptive isogeometric analysis: Local refinement and hierarchical refinement

We present 2 adaptive refinement techniques, namely, adaptive local refinement and adaptive hierarchical refinement, for isogeometric analysis. An element-wise point of view is adopted, exploiting Bézier extraction, which facilitates the implementation of adaptive refinement in isogeometric analysis. Locally refined and hierarchical T-splines are used for the description of the geometry as well as for the approximation of the solution space in the analysis. The refinement is conducted with the aid of a subdivision operator, which is computed by again exploiting the Bézier extraction operator. The concept and algorithm of an element-based adaptive isogeometric analysis are illustrated. Numerical examples are given to examine the accuracy, the convergence, and the condition number.