LIGGGHTS(R)-PUBLIC 3.X vs. LIGGGHTS(R)-PUBLIC 2.X - syntax changes

Introduction:

This is a short outline of the most important changes in LIGGGHTS(R)-PUBLIC 3.X compared to LIGGGHTS(R)-PUBLIC 2.X regarding the syntax of major commands. The motivation for these changes was to make the script language more readable and to improve extendability (in the sense of object oriented programming) with respect to modelling approaches.

Commands covered by this tutorial:

  • fix wall/gran/*
  • pair_style gran/*

Changes in syntax for each command:

Changes are indicated as follows

OLD: old_syntax
NEW: new_syntax

where old_syntax refers to the syntax used in LIGGGHTS(R)-PUBLIC 2.X and before, and new_syntax refers to the syntax used in LIGGGHTS(R)-PUBLIC 3.X.


fix wall/gran/*:

OLD: fix ID group-ID wall/gran/* WALL-OPTIONS
NEW: fix ID group-ID wall/gran MODEL-SELECTION WALL-OPTIONS MODEL-SETTINGS

MODEL-SELECTION

MODEL-SELECTION = model M [tangential T] [cohesion C] [rolling_friction R]
M = hooke | hooke/stiffness | hooke/hysteresis | hertz | hertz/stiffness
T = no_history | history
C = off | sjkr | sjkr2 | hamaker
R = off | cdt | epsd

MODEL-SETTINGS

MODEL-SELECTION = [tangential_damping (on**|off)] [absolute_damping (on|**off)] [viscous (on|**off**)]

Examples

OLD: fix ID group-ID wall/gran/hertz/history mesh n_meshes 2 meshes cad1 cad2
NEW: fix ID group-ID wall/gran model hertz tangential history mesh n_meshes 2 meshes cad1 cad2
OLD: fix ID1 group-ID wall/gran/hooke/history type 1 xplane -0.5
NEW: fix ID1 group-ID wall/gran model hooke tangential history type 1 xplane -0.5
OLD: fix ID1 group-ID wall/gran/hertz/history primitive type 1 xplane -0.5 rolling_friction cdt
NEW: fix ID1 group-ID wall/gran model hertz tangential history rolling_friction cdt primitive type 1 xplane -0.5
OLD: fix ID group-ID wall/gran/hertz/history primitive type 1 xplane -0.5 0.5 cohesion sjkr
NEW: fix ID group-ID wall/gran model hertz tangential history cohesion sjkr primitive type 1 xplane -0.5 0.5
OLD: fix ID group-ID wall/gran/hertz/history primitive type 1 zcylinder 0.05 0. 0. tangential_damping off
NEW: fix ID group-ID wall/gran model hertz tangential history primitive type 1 zcylinder 0.05 0. 0. tangential_damping off

pair_style gran/*:

OLD: pair_style gran/* MODEL-SETTINGS
NEW: pair_style gran  MODEL-SELECTION MODEL-SETTINGS

MODEL-SELECTION

Same as in fix wall/gran/*

MODEL-SETTINGS

Same as in fix wall/gran/*

Examples

OLD: pair_style gran/hertz/history
NEW: pair_style gran model hertz tangential history
OLD: pair_style gran/hertz/history rolling_friction cdt
NEW: pair_style gran model hertz tangential history rolling_friction cdt
OLD: pair_style gran/hertz/history cohesion sjkr
NEW: pair_style gran model hertz tangential history cohesion sjkr
OLD: pair_style gran/hertz/history tangential_damping off
OLD: pair_style gran model hertz tangential history tangential_damping off