Custom boundary conditions

[epectation]

When using RZ geometry, can the boundary condition at r=0 only be 'none'? This causes particles to freely pass through the z-axis, which looks like reflection in a 2D plot. Is it possible to define a boundary condition by myself, or what method should I use to achieve an effect similar to inelastic collisions?

[RemiLehe]

Thanks for your question.

The boundary condition at r=0 can indeed only be none.
If you would like to have a different boundary condition (perhaps at r slightly above r=0) you can potentially use embedded boundaries. By default, this will absorb all particles that hit the embedded boundary, but you can use Python callbacks to implement more sophisticated particle boundary interaction. See for instance

• https://github.com/BLAST-WarpX/warpx/blob/development/Examples/Tests/particle_boundary_interaction/inputs_test_rz_particle_boundary_interaction_picmi.py
• https://github.com/BLAST-WarpX/warpx/blob/development/Examples/Tests/secondary_ion_emission/inputs_test_rz_secondary_ion_emission_picmi.py