mirror of https://github.com/lammps/lammps.git
72 lines
1.4 KiB
Plaintext
72 lines
1.4 KiB
Plaintext
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# sample LAMMPS input script for viscosity of 2d LJ liquid
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# Muller-Plathe via fix viscosity
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# settings
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variable x equal 20
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variable y equal 20
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variable rho equal 0.6
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variable t equal 1.0
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variable rc equal 2.5
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# problem setup
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units lj
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dimension 2
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atom_style atomic
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neigh_modify delay 0 every 1
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lattice sq2 ${rho}
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region simbox block 0 $x 0 $y -0.1 0.1
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create_box 1 simbox
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create_atoms 1 box
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pair_style lj/cut ${rc}
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pair_coeff * * 1 1
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mass * 1.0
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velocity all create $t 97287
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fix 1 all nve
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fix 2 all langevin $t $t 0.1 498094
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fix 3 all enforce2d
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# equilibration run
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thermo 1000
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run 5000
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unfix 2
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# turn on Muller-Plathe driving force and equilibrate some more
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velocity all scale $t
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fix 4 all viscosity 100 x y 20
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fix 5 all ave/spatial 20 50 1000 y center 0.05 vx &
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units reduced file profile.mp.2d
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# equilibration run
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variable dVx equal f_5[10][3]-f_5[1][3]
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thermo 1000
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thermo_style custom step temp epair etotal press f_4 v_dVx
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run 20000
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# data gathering run
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# reset fix viscosity to zero flux accumulation
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unfix 4
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fix 4 all viscosity 100 x y 20
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variable visc equal -(f_4/(2*(step*0.005-125)*lx+1.0e-10))/(v_dVx/(ly/2))
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fix vave all ave/time 1000 1 1000 v_visc ave running start 26000
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thermo_style custom step temp f_4 v_dVx v_visc f_vave
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#dump 1 all custom 100 dump.mp.2d id type x y z vx
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run 50000
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