Re: [sparta-users] [EXTERNAL] surf/move

[Moore, S. <st...@sa...>]

Hi Madan, the particles are deleted immediately upon contact. See the doc page
https://sparta.github.io/doc/move_surf.html for more details:
"After the surface has been moved, then all particles in grid cells that meet either of these criteria are deleted:

  *   the grid cell is now inside a surface
  *   the grid cell overlaps with a surface element that moved

This is to prevent particles from ending up inside surface objects."

Stan
________________________________
From: Madan B K via sparta-users <spa...@li...>
Sent: Monday, October 20, 2025 6:51 PM
To: SPARTA Mailing list <spa...@li...>
Subject: [EXTERNAL] [sparta-users] surf/move

Hello SPARTA developers,
I have a question about how particles interact with moving surfaces when using the fix move/surf (and fix move/surf/kk) command.
When a surface element is moved using this fix, do particles bounce when they collide with the surface (as in the usual reflection model), or are they deleted immediately upon contact — as if they vanish as soon as they intersect with the moving surface?
I’m trying to clarify whether the particle-surface interaction is handled dynamically (reflective) or instant deletion when overlap occurs during motion.
Thank you for your time and for maintaining SPARTA!

Regards,
Madan B K