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Delete fix_wall_ACL.txt

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"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)
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fix wall/ACL command :h3
fix wall/ACL/kk command :h3
[Syntax:]
fix ID group-ID wall/ACL face pos temp velx vely velz keyword value ... :pre
ID, group-ID are documented in "fix"_fix.html command :ulb,l
wall/ACL = style name of this fix command :l
one or more face/arg pairs may be appended :l
face = {xlo} or {xhi} or {ylo} or {yhi} or {zlo} or {zhi} :l
{xlo},{ylo},{zlo} pos = EDGE or constant or variable
EDGE = current lo edge of simulation box
constant = number like 0.0 or -30.0 (distance units)
variable = "equal-style variable"_variable.html like v_x or v_wiggle
temp = wall temperature
velx, vely, velz = wall velocity along x, y, z directions
accomx, accomy, accomz = accommodation coefficients along x, y, z directions
{xhi},{yhi},{zhi} pos = EDGE or constant or variable
EDGE = current hi edge of simulation box
constant = number like 50.0 or 100.3 (distance units)
variable = "equal-style variable"_variable.html like v_x or v_wiggle
temp = wall temperature
velx, vely, velz = wall velocity along x, y, z directions
accomx, accomy, accomz = accommodation coefficients along x, y, z directions :pre
zero or more keyword/value pairs may be appended :l
keyword = {units} :l
{units} value = {lattice} or {box}
{lattice} = the wall position is defined in lattice units
{box} = the wall position is defined in simulation box units :pre
:ule
[Examples:]
fix ywalls all wall/ACL xlo EDGE 300 0.1 0.1 0 0.8 0.8 0.9 xhi EDGE 200 0.1 0.1 0 0.8 0.8 0.9
fix ywalls all wall/ACL xlo 300 0.1 0.1 0 ylo 300 0.1 0.1 0 0.9 0.8 0.7 units box :pre
[Description:]
In the USER-GWBC package, the three fixes wall/diffusive, wall/ACL, wall/Maxwell are implementations of stochastic wall models. The acronym GWBC stands for Gas-Wall Boundary Conditions. Like fix wall/reflect, these fixes bound the simulation with one or more walls by puting back atoms inside whenever they cross through the wall, i.e collision event. While the wall/reflect corrsponds to mirror reflection where the reflected velocity is deterministic depending on the incoming velocity, the reflected velocity in the stochastic wall models is random. The randomness accounts for the nature of the wall, the thermal motion of the wall atoms or the surface roughness. These models are useful for simulation gas flows without describing atomistically the wall boundary and thus save significantly computation cost.
This model is proposed by Cercignani-Lampis (CL) in 1971, which can model the gas-wall collision more realistically. Instead of mixing wall/reflect and wall/diffusive as in Maxwell model, the CL model used shifted MB distribution for the tangential velocity and exponential bessel for the normal velocity. Two accommodation coefficients are used: one for the tangential velocity (isotropic) and one for the normal kinetic energy. In the anisotropic version (ACL) which can account for the anisotropy of the wall surface, there are three coefficients: two for the tangential velocity (two components) and one for the kinetic energy. The code will recognize automatically the normal direction of the wall and the other two tangential directions. For example, if accomx = 0.5, accomy = 0.2, accomz = 0.3 and the wall is normal to direction y, accomx and accomz are the tangential velocity accommodation coefficients and accomy is the normal kinetic energy accommodation coefficients.
The {units} keyword determines the distance units used to define a wall position
A {box} value selects standard distance units as defined by the "units"_units.html command, e.g. Angstroms for units = real or metal.
A {lattice} value means the distance units are in lattice spacings. The "lattice"_lattice.html command must have been previously used to define the lattice spacings.
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[Restrictions:]
Due to its properties, this fix has has the same limitation as the the wall/reflect. Any dimension (xyz) that has a wall must be non-periodic. It shoudld not be used with rigid bodies such as those defined by a "fix rigid" command.
[Related commands:]
"fix wall/reflect"_fix_wall_reflect.html, "fix wall/Maxwell"_fix_wall_Maxwell.html, "fix wall/diffusive"_fix_wall_diffusive.html
[Default:] none
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