This paper describes the development and application of inflow and outflow boundary conditions (BCs) for the material point method (MPM) in order to simulate fluid flow problems. This corresponds to velocity and pressure controlled BCs. Due to the coupled Lagrangian and Eulerian description of the fluid motion in MPM it is necessary to add and remove material points, with appropriate kinematic properties, to and from the computational domain. The newly-developed BCs have been used to simulate uniform open channel flow and the phenomenon of free overfall in open channels, which is transient conditions leading to non-uniform flow due to a sudden bed level drop. It is shown that the numerical results predict well the flow geometry including end depth ratio, pressure distribution and accelerations, therefore the velocities and displacements.@en

This paper describes current work on the implementation of non-trivial boundary conditions (BCs) for improving the general applicability of the Material Point Method (MPM) to geotechnical boundary values problems. It summarises novel boundary treatments (non-trivial BCs) in MPM for (i) flow conditions, as well as (ii) the application of a surface traction on a moving boundary for solid materials. Both treatments are required, for example, to estimate the consequence of slope failure in geotechnical engineering. the flow condition BCs have been used to stimulate a subcritical flow and the surface traction BC has been applied on top of aslope leading to failure. Both examples show that these new treatments are useful in solving practical problems.@en