Morphology characterization and discrete element modeling of coral sand with intraparticle voids

Coral sand is the main geomaterial on tropical reefs and its constituent particles are featured with complex shapes and abundant intraparticle voids. This work presents a discrete element method (DEM)-based numerical modeling of coral sand in consideration of both the irregular shape and intraparticle voids of particles. To develop the DEM model for coral sand, the acquisition and characterization of coral sand particles are first introduced. A signed distance field-based DEM applicable to arbitrarily irregular-shaped particles is then presented, in conjunction with two versatile particle models, namely spherical harmonics (SH) and level set (LS). To generate virtual coral sand particles that conform to target morphology characteristics, the combined random field and SH approach and the remedy to elongated particles are also presented. The developed DEM model is calibrated and validated against laboratory column collapse tests, where the agreements between numerical simulations and laboratory experiments demonstrate the good validity and accuracy of DEM model for coral sand. The performance of SH and LS particle models are also compared, providing a useful reference for the selection of appropriate particle models for coral sand in practice.