14.3.2.1. Dambreak Analysis using background mesh

  1. The source code is shown below, which can be downloaded here.
  2. Run the source code in your favorite Python program.
  3. The ParaView is needed to view the results. To view the displaced shape of fluid, use the “Warp By Vector” filter with scale factor = 1.0.
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import os
import os.path
import openseespy.opensees as ops

# ------------------------------
# Start of model generation
# -----------------------------

# wipe all previous objects
ops.wipe()

# create a model with fluid
ops.model('basic', '-ndm', 2, '-ndf', 2)

# geometric
L = 0.146
H = L * 2
h = L / 40

# number of particles per cell in each direction
numx = 3.0
numy = 3.0

# material
rho = 1000.0
mu = 0.0001
b1 = 0.0
b2 = -9.81
thk = 0.012
kappa = -1.0

# analysis
dtmax = 1e-3
dtmin = 1e-3
totaltime = 1.0
filename = 'dambreak-bg'

# recorder
ops.recorder('BgPVD', filename, 'disp', 'vel', 'pressure', '-dT', 1e-3)
if not os.path.exists(filename):
    os.makedirs(filename)

# fluid particles
ndf = 2

# total number of particles in each direction
nx = round(L / h * numx)
ny = round(H / h * numy)

# create particles
eleArgs = ['PFEMElementBubble', rho, mu, b1, b2, thk, kappa]
partArgs = ['quad', 0.0, 0.0, L, 0.0, L, H, 0.0, H, nx, ny]
parttag = 1
ops.mesh('part', parttag, *partArgs, *eleArgs, '-vel', 0.0, 0.0)

print('num particles =', nx * ny)

# wall
ops.node(1, 0.0, H)
ops.node(2, 0.0, 0.0)
ops.node(3, 4 * L, 0.0)
ops.node(4, 4 * L, H)

walltag = 2
wallid = 1
ops.mesh('line', walltag, 4, 1, 2, 3, 4, wallid, ndf, h)

wallnodes = ops.getNodeTags('-mesh', walltag)

for nd in wallnodes:
    ops.fix(nd, 1, 1)

# background mesh
lower = [-h, -h]
upper = [4 * L + L, H + L]

ops.mesh('bg', h, *lower, *upper,
         '-structure', wallid, len(wallnodes), *wallnodes)

# create constraint object
ops.constraints('Plain')

# create numberer object
ops.numberer('Plain')

# create convergence test object
ops.test('PFEM', 1e-5, 1e-5, 1e-5, 1e-5, 1e-5, 1e-5, 10, 3, 1, 2)

# create algorithm object
ops.algorithm('Newton')

# create integrator object
ops.integrator('PFEM', 0.5, 0.25)

# create SOE object
ops.system('PFEM')
# ops.system('PFEM', '-mumps) Linux version can use mumps

# create analysis object
ops.analysis('PFEM', dtmax, dtmin, b2)

# analysis
while ops.getTime() < totaltime:

    # analysis
    if ops.analyze() < 0:
        break

    ops.remesh()

print("==========================================")