pre_exchange never called

Hello,

I've found that in coupled simulations, the pre_exchange module of a fix might never be called. This module is only called when the neighbourlist is rebuild during integration. As in a coupled simulation many short runs are done, the neighbourlist might never be rebuild. Instead, the initial build from the set-up of the run is used for the entire coupling interval. This leads to features as fix massflow/mesh ... delete_atoms yes not working, as they rely on the pre_exchange module. Right now, I have worked around by setting the skinsize very small and thus forcing LIGGGHTS to rebuild the list, but this is of course a waste of resources and time. Maybe, pre_exchange can be called in the last timestep as well, to solve this problem?

Kind regards,

Tim Nijssen
Eindhoven University of Technology