Simulation of vortex breakdown using adaptive grid refinement with vortex-center identification

A topological-feature adaptation method is proposed to compute vortical flows around a delta wing at high incidence. Vortex-center identification based on the locally applied critical-point method is utilized as an indicator of the grid refinement using Rivara's bisection algorithm (Rivara, M. C., "Selective Refinement/Definement Algorithms for Sequences of Nested Triangulations," International Journal of Numerical Methods in Engineering, Vol. 28, 1989, pp. 2889-2906). The three-dimensional Navier-Stokes equations are solved using the hybrid unstructured grid. The computed results show that the refinement at the vortex core is effective to improve the numerical accuracy of the flow around a delta wing. The present feature-adaptive refinement is especially effective to improve the prediction of the vortex breakdown positions at high incidence. The results indicate the importance of the resolution at the vortex core for an accurate prediction of vortex-dominated flowfields.