Axisymmetric viscoplastic dambreaks and the slump test

We report computations of the axisymmetric slump of viscoplastic fluid using the volume-of-fluid (VOF) method. The constitutive law is dealt with by either regularization or the augmented-Lagrangian method. The interface is tracked by the PLIC scheme, modified in order to avoid resolution issues associated with the over-ridden finger of ambient fluid that results from the no slip condition and the resulting inability to move the contact line. Numerical results are compared with asymptotic analyses for shallow gravity currents or slender vertical columns. The critical yield stress for failure is computed and bounded analytically using plasticity methods. The simulations are compared with experiments either taken from existing literature or performed using Carbopol. The comparison is satisfying for lower yield stresses; discrepancies for larger yield stresses suggest that the mechanism of release may affect the experiments.