/usr/lib/python2.7/dist-packages/PySPH-1.0a4.dev0-py2.7-linux-x86_64.egg/pysph/examples/surface_tension/khi_tvf.py is in python-pysph 0~20160514.git91867dc-4build1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 | """2D Kelvin Helmoltz Instability example using TVF. (1 hour)
"""
import numpy
# Particle generator
from pysph.base.utils import get_particle_array
from pysph.base.kernels import WendlandQuintic
# SPH Equations and Group
from pysph.sph.equation import Group
from pysph.sph.wc.viscosity import ClearyArtificialViscosity
from pysph.sph.wc.transport_velocity import SummationDensity, MomentumEquationPressureGradient,\
SolidWallPressureBC, SolidWallNoSlipBC, SetWallVelocity, \
StateEquation, MomentumEquationArtificialStress, MomentumEquationViscosity
from pysph.sph.surface_tension import ColorGradientUsingNumberDensity, \
InterfaceCurvatureFromNumberDensity, ShadlooYildizSurfaceTensionForce,\
SmoothedColor
from pysph.sph.gas_dynamics.basic import ScaleSmoothingLength
# PySPH solver and application
from pysph.solver.application import Application
from pysph.solver.solver import Solver
# Integrators and Steppers
from pysph.sph.integrator_step import TransportVelocityStep
from pysph.sph.integrator import PECIntegrator
# Domain manager for periodic domains
from pysph.base.nnps import DomainManager
# problem parameters
dim = 2
domain_width = 1.0
domain_height = 1.0
# numerical constants
gy = -9.81
alpha = 0.001
wavelength = 1.0
wavenumber = 2*numpy.pi/wavelength
Ri = 0.05
rho0 = rho1 = 1000.0
rho2 = 1*rho1
U = 0.5
sigma = Ri * (rho1*rho2) * (2*U)**2/(wavenumber*(rho1 + rho2))
# initial perturbation amplitude
psi0 = 0.03*domain_height
# discretization parameters
nghost_layers = 5
dx = dy = 0.01
dxb2 = dyb2 = 0.5 * dx
volume = dx*dx
hdx = 1.5
h0 = hdx * dx
rho0 = 1000.0
c0 = 25.0
p0 = c0*c0*rho0
nu = 0.125 * alpha * h0 * c0
# time steps
tf = 3.0
dt_cfl = 0.25 * h0/( 1.1*c0 )
dt_viscous = 0.125 * h0**2/nu
dt_force = 1.0
dt = 0.8 * min(dt_cfl, dt_viscous, dt_force)
class KHITVF(Application):
def create_particles(self):
ghost_extent = (nghost_layers + 0.5)*dx
x, y = numpy.mgrid[ dxb2:domain_width:dx, -ghost_extent:domain_height+ghost_extent:dy ]
x = x.ravel(); y = y.ravel()
m = numpy.ones_like(x) * volume * rho0
rho = numpy.ones_like(x) * rho0
h = numpy.ones_like(x) * h0
cs = numpy.ones_like(x) * c0
# additional properties required for the fluid.
additional_props = [
# volume inverse or number density
'V',
# color and gradients
'color', 'scolor', 'cx', 'cy', 'cz', 'cx2', 'cy2', 'cz2',
# discretized interface normals and dirac delta
'nx', 'ny', 'nz', 'ddelta',
# interface curvature
'kappa',
# transport velocities
'uhat', 'vhat', 'what', 'auhat', 'avhat', 'awhat',
# imposed accelerations on the solid wall
'ax', 'ay', 'az', 'wij',
# velocity of magnitude squared
'vmag2',
# variable to indicate reliable normals and normalizing
# constant
'N', 'wij_sum',
]
# get the fluid particle array
fluid = get_particle_array(
name='fluid', x=x, y=y, h=h, m=m, rho=rho, cs=cs,
additional_props=additional_props)
# set the fluid velocity with respect to the sinusoidal
# perturbation
fluid.u[:] = -U
mode = 1
for i in range(len(fluid.x)):
if fluid.y[i] > domain_height/2 + psi0*domain_height*numpy.sin(2*numpy.pi*fluid.x[i]/(mode*domain_width)):
fluid.u[i] = U
fluid.color[i] = 1
fluid.rho[i] = rho1
fluid.m[i] = volume*rho1
else:
fluid.rho[i] = rho2
fluid.m[i] = rho2/rho1*volume*rho2
# extract the top and bottom boundary particles
indices = numpy.where( fluid.y > domain_height )[0]
wall = fluid.extract_particles( indices )
fluid.remove_particles( indices )
indices = numpy.where( fluid.y < 0 )[0]
bottom = fluid.extract_particles( indices )
fluid.remove_particles( indices )
# concatenate the two boundaries
wall.append_parray( bottom )
wall.set_name( 'wall' )
# set the number density initially for all particles
fluid.V[:] = 1./volume
wall.V[:] = 1./volume
# set additional output arrays for the fluid
fluid.add_output_arrays(['V', 'color', 'cx', 'cy', 'nx', 'ny', 'ddelta',
'kappa', 'N', 'p', 'rho'])
# extrapolated velocities for the wall
for name in ['uf', 'vf', 'wf']:
wall.add_property(name)
# dummy velocities for the wall
# required for the no-slip BC
for name in ['ug','vg','wg']:
wall.add_property(name)
print("2D KHI with %d fluid particles and %d wall particles"%(
fluid.get_number_of_particles(), wall.get_number_of_particles()))
return [fluid, wall]
def create_domain(self):
return DomainManager(xmin=0, xmax=domain_width, ymin=0, ymax=domain_height,
periodic_in_x=True, periodic_in_y=False)
def create_solver(self):
kernel = WendlandQuintic(dim=2)
integrator = PECIntegrator( fluid=TransportVelocityStep() )
solver = Solver(
kernel=kernel, dim=dim, integrator=integrator,
dt=dt, tf=tf, adaptive_timestep=False)
return solver
def create_equations(self):
tvf_equations = [
# We first compute the mass and number density of the fluid
# phase. This is used in all force computations henceforth. The
# number density (1/volume) is explicitly set for the solid phase
# and this isn't modified for the simulation.
Group(equations=[
SummationDensity( dest='fluid', sources=['fluid', 'wall'] )
] ),
# Given the updated number density for the fluid, we can update
# the fluid pressure. Additionally, we can extrapolate the fluid
# velocity to the wall for the no-slip boundary
# condition. Also compute the smoothed color based on the color
# index for a particle.
Group(equations=[
StateEquation(dest='fluid', sources=None, rho0=rho0,
p0=p0, b=1.0),
SetWallVelocity(dest='wall', sources=['fluid']),
SmoothedColor( dest='fluid', sources=['fluid'] ),
] ),
#################################################################
# Begin Surface tension formulation
#################################################################
# Scale the smoothing lengths to determine the interface
# quantities. The NNPS need not be updated since the smoothing
# length is decreased.
Group(equations=[
ScaleSmoothingLength(dest='fluid', sources=None, factor=0.8)
], update_nnps=False ),
# Compute the gradient of the color function with respect to the
# new smoothing length. At the end of this Group, we will have the
# interface normals and the discretized dirac delta function for
# the fluid-fluid interface.
Group(equations=[
ColorGradientUsingNumberDensity(dest='fluid', sources=['fluid', 'wall'],
epsilon=0.01/h0),
],
),
# Compute the interface curvature using the modified smoothing
# length and interface normals computed in the previous Group.
Group(equations=[
InterfaceCurvatureFromNumberDensity(dest='fluid', sources=['fluid'],
with_morris_correction=True),
], ),
# Now rescale the smoothing length to the original value for the
# rest of the computations.
Group(equations=[
ScaleSmoothingLength(dest='fluid', sources=None, factor=1.25)
], update_nnps=False,
),
#################################################################
# End Surface tension formulation
#################################################################
# Once the pressure for the fluid phase has been updated via the
# state-equation, we can extrapolate the pressure to the wall
# ghost particles. After this group, the density and pressure of
# the boundary particles has been updated and can be used in the
# integration equations.
Group(
equations=[
SolidWallPressureBC(dest='wall', sources=['fluid'], p0=p0, rho0=rho0,
gy=gy),
], ),
# The main acceleration block
Group(
equations=[
# Gradient of pressure for the fluid phase using the
# number density formulation. No penetration boundary
# condition using Adami et al's generalized wall boundary
# condition. The extrapolated pressure and density on the
# wall particles is used in the gradient of pressure to
# simulate a repulsive force.
MomentumEquationPressureGradient(
dest='fluid', sources=['fluid', 'wall'], pb=p0,
gy=gy),
# Artificial viscosity for the fluid phase.
MomentumEquationViscosity(
dest='fluid', sources=['fluid'], nu=nu),
# No-slip boundary condition using Adami et al's
# generalized wall boundary condition. This equation
# basically computes the viscous contribution on the fluid
# from the wall particles.
SolidWallNoSlipBC(dest='fluid', sources=['wall'], nu=nu),
# Surface tension force for the SY11 formulation
ShadlooYildizSurfaceTensionForce(dest='fluid', sources=None, sigma=sigma),
# Artificial stress for the fluid phase
MomentumEquationArtificialStress(dest='fluid', sources=['fluid']),
], )
]
return tvf_equations
if __name__ == '__main__':
app = KHITVF()
app.run()
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