  A space-time framework is applied to simulate dense granular flow. Two
different numerical experiments are performed: a column collapse and a dam
break on an inclined plane. The experiments are modeled as two-phase flows. The
dense granular material is represented by a constitutive model, the
$\mu$($I$)-rheology, that is based on the Coulomb's friction law, such that the
normal stress applied by the pressure is related to the tangential stress. The
model represents a complex shear thinning viscoplastic material behavior. The
interface between the dense granular material and the surrounding light fluid
is captured with a level set function. Due to discontinuities close to the the
interface, the mesh requires a sufficient resolution. The space-time approach
allows unstructured meshes in time and, therefore a well refined mesh in the
temporal direction around the interface. In this study, results and performance
of a flat and a simplex space time discretization are verified and analyzed.
