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lammps/examples/USER/sph/cavity_flow/cavity_flow.lmp

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dimension 2
units si
atom_style meso
# create simulation box
region box block -0.050e-3 1.044e-3 -0.05e-3 1.044e-3 -1.0e-6 1.0e-6 units box
create_box 3 box
# create fluid particles
region fluid block 0.0001e-3 0.999e-3 0.0001e-3 0.999e-3 EDGE EDGE side in units box
lattice sq 0.025e-3
create_atoms 1 region fluid
# create bottom, left, and right wall
region walls block 0.0001e-3 0.999e-3 0.0001e-3 EDGE EDGE EDGE side out units box
lattice sq2 0.025e-3
create_atoms 2 region walls
# create a driver strip of particles, which exerts shear forces on the fluid
region driver block EDGE EDGE 0.999e-3 EDGE EDGE EDGE side in units box
create_atoms 3 region driver
group fluid type 1
group walls type 2
group driver type 3
group integrate_full union fluid driver
mass 3 2.0e-7
mass 2 2.0e-7
mass 1 4.0e-7
set group all meso/rho 1000.0
# use Tait's EOS in combination with Morris' laminar viscosity.
# We set rho_0 = 1000 kg/m^3, c = 0.1 m/s, h = 6.5e-5 m.
# The dynamic viscosity is set to 1.0e-3 Pa s, corresponding to a kinematic viscosity of 1.0e-6 m^2/s
pair_style hybrid sph/taitwater/morris
pair_coeff * * sph/taitwater/morris 1000 0.1 1.0e-3 6.5e-5
pair_coeff 2 3 none # exclude interaction between walls and shear driver
compute rho_peratom all meso/rho/atom
compute e_peratom all meso/e/atom
compute ke_peratom all ke/atom
compute esph all reduce sum c_e_peratom
compute ke all ke
variable etot equal c_ke+c_esph
# assign a constant velocity to shear driver
velocity driver set 0.001 0.0 0.0 units box
fix freeze_fix driver setforce 0.0 0.0 0.0
# do full time integration for shear driver and fluid, but keep walls stationary
fix integrate_fix_full integrate_full meso
fix integrate_fix_stationary walls meso/stationary
dump dump_id all custom 100 dump.lammpstrj id type xs ys zs vx vy c_rho_peratom c_e_peratom
dump_modify dump_id first yes
thermo 100
thermo_style custom step c_esph v_etot
thermo_modify norm no
neighbor 3.0e-6 bin
timestep 5.0e-5
run 4000