Direct Numerical Simulations of bed-load transport with non-spherical particles

This thesis presents the first highly resolved numerical
simulations of sediment transport with a multitude of
ellipsoidal particles of various shapes. To realize these
simulations, the in-house code PRIME was extended with a
constraint-based collision model for ellipsoids in a viscous
media. Four phase-resolving Direct Numerical Simulations
are conducted with monodisperse particles of different
shapes (sphere, oblate, prolate, and tri-axial ellipsoid). The
important quantities studied here are the mean particle
velocities, the characteristic saltation length and period, the
sediment-bed permeability, and the mean particle transport
rate. By and large, the same two opposite extremes are
observed in almost all mean quantities related to the disperse
phase. At one end are the oblates, while at the other end are
the spheres. The ellipsoids, which represent medium-size
sand particles, behave in between these two extreme cases.
Finally, an additional simulation is conducted using a set of
particles which mimics a natural sand sample. To the best of
the author’s knowledge, this simulation is the first of its kind
and brings DNS of sediment transport with phase-resolved
particles nearer to reality.