Application of grid-convergence-index to the confined vortex-breakdown flows

Abstract

According to a recent experimental measurement, the limiting Reynolds number Re_c for the appearance of vortex breakdown bubbles confined in a cylindrical container is shifted toward higher values of Re than that reported in the classical experimental study by Escudier. In order to study this point, numerical simulation is performed using finite-difference codes. Grid-convergence-index (GCI) is estimated and grid-independent-solution (GIS) is derived by applying Richardson extrapolation. Whether the numerical solution shows higher values of limiting Re_c as in the recent PIV measurement or lower values of Re as in the classical dye-injection observation by Escudier is assessed.