The calculation of settling speed of coarse particlesis firstly addressed, with accelerated Stokesian dynamicswithout adjustable parameters, in which far field force actingon the particle instead of particle velocity is chosen asdependent variables to consider inter-particle hydrodynamicinteractions. The sedimentation of a simple cubic array ofspherical particles is simulated and compared to the resultsavailable to verify and validate the numerical code andcomputational scheme. The improved method keeps the samecomputational cost of the order O (N log N) as usualaccelerated Stokesian dynamics does. Then, more realisticrandom suspension sedimentation is investigated with thehelp of Mont Carlo method. The computational results agreewell with experimental fitting. Finally, the sedimentation offiner cohesive particle, which is often observed in estuaryenvironment, is presented as a further application in coastalengineering.
Long Wang Jiachun Li Jifu Zhou Institute of Mechanics, CAS, 100190 Beijing, China
With the finite volume method, a 2D numerical model for seepage in unsaturated soil has been established to study the rainfall infiltration in the fractured slope. The result shows that more rain may infiltrate into the slope due to existing fracture and then the pore pressure rises correspondingly. Very probably, it is one of the crucial factors accounting for slope failure. Furthermore a preliminary study has been conducted to investigate the influence of various fracture and rainfall factors such as the depth, width and location of a crack, surface condition, rainfall intensity and duration. Pore pressure and water volumetric content during the transient seepage are carefully examined to reveal the intrinsic mechanism.
