77 lines
3.8 KiB
Plaintext
Executable File
77 lines
3.8 KiB
Plaintext
Executable File
#===========================================================================#
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# System of 2 pairs of rigid particles moving towards one another. #
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# At each timestep, the hydrodynamic force acting on one of these four #
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# rigid particles is printed to the screen. #
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# #
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# Here, gamma (used in the calculation of the particle-fluid interaction #
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# force) is set by the user (gamma = 3.303 for this simulation...this #
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# value has been calibrated a priori through simulations of the drag #
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# force acting on a single particle of the same radius). #
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# #
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# Sample output from this run can be found in the file: #
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# 'fourspheres_velocity0d0001_setgamma.out' #
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#===========================================================================#
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units micro
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dimension 3
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boundary p p p
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atom_style atomic
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#----------------------------------------------------------------------------
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# Need a neighbor bin size smaller than the lattice-Boltzmann grid spacing
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# to ensure that the particles belonging to a given processor remain inside
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# that processors lattice-Boltzmann grid.
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# The arguments for neigh_modify have been set to "delay 0 every 1", again
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# to ensure that the particles belonging to a given processor remain inside
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# that processors lattice-Boltzmann grid. However, these values can likely
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# be somewhat increased without issue. If a problem does arise (a particle
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# is outside of its processors LB grid) an error message is printed and
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# the simulation is terminated.
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#----------------------------------------------------------------------------
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neighbor 1.0 bin
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neigh_modify delay 0 every 1 exclude type 1 1
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read_data data.four
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#----------------------------------------------------------------------------
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# None of the particles interact with one another.
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#----------------------------------------------------------------------------
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pair_style lj/cut 2.45
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pair_coeff * * 0.0 0.0 2.45
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mass * 1.0
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timestep 4.0
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group sphere1 id <> 1 320
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group sphere2 id <> 321 640
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group sphere3 id <> 641 960
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group sphere4 id <> 961 1280
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velocity sphere1 set 0.0 0.0001 0.0 units box
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velocity sphere2 set 0.0 -0.0001 0.0 units box
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velocity sphere3 set 0.0 0.0001 0.0 units box
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velocity sphere4 set 0.0 -0.0001 0.0 units box
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#---------------------------------------------------------------------------
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# Create a lattice-Boltzmann fluid covering the simulation domain.
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# All of the particles in the simulation apply a force to the fluid.
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# Use the LB integration scheme of Ollila et. al. (for stability reasons,
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# this integration scheme should be used when a large user set value for
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# gamma is specified), a fluid density = 1.0, fluid viscosity = 1.0, value
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# for gamma=3.303, lattice spacing dx=4.0, and mass unit, dm=10.0.
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# Print the force and torque acting on one of the spherical colloidal objects
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# to the screen at each timestep.
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#----------------------------------------------------------------------------
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fix 1 all lb/fluid 1 2 1.0 1.0 setGamma 3.303 dx 4.0 dm 10.0 calcforce 20 sphere1
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#---------------------------------------------------------------------------
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# For this simulation the colloidal particles move at a constant velocity
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# through the fluid. As such, we do not wish to apply the force from
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# the fluid back onto these objects. Therefore, we do not use any of the
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# viscous_lb, rigid_pc_sphere, or pc fixes, and simply integrate the
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# particle motions using one of the built-in LAMMPS integrators.
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#---------------------------------------------------------------------------
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fix 2 all nve
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run 300000
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