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### fix smd/integrate_ulsph command

Syntax:

    fix ID group-ID smd/integrate_ulsph keyword

- ID, group-ID are documented in fix command
- smd/integrate_ulsph = style name of this fix command
- zero or more keyword/value pairs may be appended

keyword = adjust_radius or limit_velocity

adjust_radius values = adjust_radius_factor min_nn max_nn adjust_radius_factor = factor which scale the smooth/kernel radius min_nn = minimum number of neighbors max_nn = maximum number of neighbors limit_velocity values = max_velocity max_velocity = maximum allowed velocity.

Examples:

    fix 1 all smd/integrate_ulsph adjust_radius 1.02 25 50

    fix 1 all smd/integrate_ulsph limit_velocity 1000

Description:

The fix performs explicit time integration for particles which interact with the updated Lagrangian SPH pair style. See this PDF guide to using Smooth Mach Dynamics in LAMMPS.

The adjust_radius keyword activates dynamic adjustment of the per-particle SPH smoothing kernel radius such that the number of neighbors per particles remains within the interval min_nn to max_nn. The parameter adjust_radius_factor determines the amount of adjustment per timestep. Typical values are adjust_radius_factor=1.02, min_nn=15, and max_nn=20.

The limit_velocity keyword will control the velocity, scaling the norm of the velocity vector to max_vel in case it exceeds this velocity limit.

Restart, fix_modify, output, run start/stop, minimize info:

Currently, no part of USER-SMD supports restarting nor minimization. This fix has no outputs.

Restrictions:

This fix is part of the USER-SMD package. It is only enabled if LAMMPS was built with that package. See the Making LAMMPS section for more info.

Related commands:

Default: none