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lammps/examples/USER/lb/planewall/in.planewall_set_gamma
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in.planewall_set_gamma
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#===========================================================================#
# Rigid sphere freely moving near a stationary plane wall in a system #
# undergoing shear flow. #
# Every 10 time steps the center of mass velocity and angular velocity of #
# the sphere are printed to the screen. #
# #
# Here, gamma (used in the calculation of the particle-fluid interaction #
# force) is set by the user (gamma = 13.655 for this simulation...this #
# value has been calibrated a priori through simulations of the drag #
# force acting on a single particle of the same radius). #
# #
# Sample output from this run can be found in the file: #
# 'wall_setgamma.out' #
#===========================================================================#
units micro
dimension 3
boundary p p f
atom_style atomic
#----------------------------------------------------------------------------
# Need a neighbor bin size smaller than the lattice-Boltzmann grid spacing
# to ensure that the particles belonging to a given processor remain inside
# that processors lattice-Boltzmann grid.
# The arguments for neigh_modify have been set to "delay 0 every 1", again
# to ensure that the particles belonging to a given processor remain inside
# that processors lattice-Boltzmann grid. However, these values can likely
# be somewhat increased without issue. If a problem does arise (a particle
# is outside of its processors LB grid) an error message is printed and
# the simulation is terminated.
#----------------------------------------------------------------------------
neighbor 1.0 bin
neigh_modify delay 0 every 1
read_data data.one_radius16d2
#----------------------------------------------------------------------------
# None of the particles interact with one another.
#----------------------------------------------------------------------------
pair_style lj/cut 2.45
pair_coeff * * 0.0 0.0 2.45
neigh_modify exclude type 1 1
mass * 100.0
timestep 4.0
group sphere1 id <> 1 320
#----------------------------------------------------------------------------
# Colloidal particle is initially stationary.
#----------------------------------------------------------------------------
velocity all set 0.0 0.0 0.0 units box
#----------------------------------------------------------------------------
# Create a lattice-Boltzmann fluid covering the simulation domain.
# All of the particles in the simulation apply a force to the fluid.
# (however, this fix does not explicitly apply a force back on to these
# particles...this is accomplished through the use of the rigid_pc_sphere
# fix).
# Use the LB integration scheme of Ollila et. al. (for stability reasons,
# this integration scheme should be used when a large user set value for
# gamma is specified), a fluid density = 1.0, fluid viscosity = 1.0, value
# for gamma=13.655, lattice spacing dx=4.0, and mass unit, dm=10.0.
# Create shear in the system, by giving the upper z-wall a velocity of 0.0001
# along the y-direction, while keeping the lower z-wall stationary.
#-----------------------------------------------------------------------------
fix 1 all lb/fluid 1 2 1.0 1.0 setGamma 13.655 dx 4.0 dm 10.0 zwall_velocity 0.0 0.0001
#----------------------------------------------------------------------------
# Apply the force from the fluid to the particles, and integrate their
# motion, constraining them to move and rotate together as a single rigid
# spherical object.
# NOTE: This fix should only be used when the user specifies a value for
# gamma (through the setGamma keyword) in the lb_fluid fix.
#----------------------------------------------------------------------------
fix 2 all lb/rigid/pc/sphere group 1 sphere1
#----------------------------------------------------------------------------
# Create variables for the center-of-mass and angular velocities, and output
# these quantities to the screen.
#----------------------------------------------------------------------------
variable vx equal vcm(all,x)
variable vy equal vcm(all,y)
variable vz equal vcm(all,z)
variable omegax equal omega(all,x)
variable omegay equal omega(all,y)
variable omegaz equal omega(all,z)
thermo_style custom v_vx v_vy v_vz v_omegax v_omegay v_omegaz
thermo 10
run 200000
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