def create_equations(self):
sy11_equations = [
Group(
equations=[SummationDensity(dest='fluid', sources=['fluid'])],
real=False),
Group(equations=[
StateEquation(dest='fluid', sources=None, rho0=rho0, p0=p0),
SY11ColorGradient(dest='fluid', sources=['fluid'])
],
real=False),
Group(equations=[
ScaleSmoothingLength(dest='fluid',
sources=None,
factor=factor1)
],
real=False,
update_nnps=True),
Group(equations=[SY11DiracDelta(dest='fluid', sources=['fluid'])],
real=False),
Group(equations=[
InterfaceCurvatureFromNumberDensity(
dest='fluid',
sources=['fluid'],
with_morris_correction=True),
],
real=False),
Group(
equations=[
ScaleSmoothingLength(dest='fluid',
sources=None,
factor=factor2)
],
real=False,
update_nnps=True,
),
Group(equations=[
MomentumEquationPressureGradient(dest='fluid',
sources=['fluid'],
pb=0.0),
MomentumEquationViscosity(dest='fluid',
sources=['fluid'],
nu=nu),
ShadlooYildizSurfaceTensionForce(dest='fluid',
sources=None,
sigma=sigma),
], )
]
adami_equations = [
Group(
equations=[SummationDensity(dest='fluid', sources=['fluid'])],
real=False),
Group(equations=[
StateEquation(dest='fluid', sources=None, rho0=rho0, p0=p0),
],
real=False),
Group(equations=[
AdamiColorGradient(dest='fluid', sources=['fluid']),
],
real=False),
Group(equations=[
AdamiReproducingDivergence(dest='fluid',
sources=['fluid'],
dim=2),
],
real=False),
Group(equations=[
MomentumEquationPressureGradient(dest='fluid',
sources=['fluid'],
pb=p0),
MomentumEquationViscosityAdami(dest='fluid',
sources=['fluid']),
CSFSurfaceTensionForceAdami(
dest='fluid',
sources=None,
)
], )
]
adami_stress_equations = [
Group(equations=[
SummationDensity(dest='fluid', sources=['fluid']),
],
real=False),
Group(equations=[
TaitEOS(dest='fluid',
sources=None,
rho0=rho0,
c0=c0,
gamma=7,
p0=p0),
],
real=False),
Group(equations=[
ColorGradientAdami(dest='fluid', sources=['fluid']),
],
real=False),
Group(equations=[
ConstructStressMatrix(dest='fluid',
sources=None,
sigma=sigma,
d=2)
],
real=False),
Group(equations=[
MomentumEquationPressureGradientAdami(dest='fluid',
sources=['fluid']),
MomentumEquationViscosityAdami(dest='fluid', sources=['fluid'
]),
SurfaceForceAdami(dest='fluid', sources=['fluid']),
]),
]
tvf_equations = [
Group(
equations=[SummationDensity(dest='fluid', sources=['fluid'])],
real=False),
Group(equations=[
StateEquation(dest='fluid', sources=None, rho0=rho0, p0=p0),
SmoothedColor(dest='fluid', sources=['fluid']),
],
real=False),
Group(equations=[
MorrisColorGradient(dest='fluid',
sources=['fluid'],
epsilon=epsilon),
],
real=False),
Group(equations=[
InterfaceCurvatureFromNumberDensity(
dest='fluid',
sources=['fluid'],
with_morris_correction=True),
],
real=False),
Group(equations=[
MomentumEquationPressureGradient(dest='fluid',
sources=['fluid'],
pb=p0),
MomentumEquationViscosity(dest='fluid',
sources=['fluid'],
nu=nu),
CSFSurfaceTensionForce(dest='fluid', sources=None,
sigma=sigma),
MomentumEquationArtificialStress(dest='fluid',
sources=['fluid']),
], )
]
morris_equations = [
Group(equations=[
SummationDensitySourceMass(dest='fluid', sources=['fluid']),
],
real=False,
update_nnps=False),
Group(equations=[
TaitEOS(dest='fluid',
sources=None,
rho0=rho0,
c0=c0,
gamma=1.0),
SmoothedColor(dest='fluid', sources=[
'fluid',
]),
ScaleSmoothingLength(dest='fluid',
sources=None,
factor=2.0 / 3.0),
],
real=False,
update_nnps=False),
Group(equations=[
MorrisColorGradient(dest='fluid',
sources=[
'fluid',
],
epsilon=epsilon),
],
real=False,
update_nnps=False),
Group(equations=[
InterfaceCurvatureFromDensity(dest='fluid',
sources=['fluid'],
with_morris_correction=True),
ScaleSmoothingLength(dest='fluid', sources=None, factor=1.5),
],
real=False,
update_nnps=False),
Group(equations=[
MomentumEquationPressureGradientMorris(dest='fluid',
sources=['fluid']),
MomentumEquationViscosityMorris(dest='fluid',
sources=['fluid']),
CSFSurfaceTensionForce(dest='fluid', sources=None,
sigma=sigma),
],
update_nnps=False)
]
if self.options.scheme == 'tvf':
return tvf_equations
elif self.options.scheme == 'adami_stress':
return adami_stress_equations
elif self.options.scheme == 'adami':
return adami_equations
elif self.options.scheme == 'shadloo':
return sy11_equations
else:
return morris_equations
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
def get_equations(self):
from pysph.sph.equation import Group
from pysph.sph.gas_dynamics.basic import (
ScaleSmoothingLength, UpdateSmoothingLengthFromVolume,
SummationDensity, IdealGasEOS, MPMAccelerations)
equations = []
# Find the optimal 'h'
if self.adaptive_h_scheme == 'mpm':
g1 = []
for fluid in self.fluids:
g1.append(
SummationDensity(dest=fluid,
sources=self.fluids,
k=self.kernel_factor,
density_iterations=True,
dim=self.dim,
htol=1e-3))
equations.append(
Group(equations=g1,
update_nnps=True,
iterate=True,
max_iterations=50))
elif self.adaptive_h_scheme == 'gsph':
group = []
for fluid in self.fluids:
group.append(
ScaleSmoothingLength(dest=fluid, sources=None, factor=2.0))
equations.append(Group(equations=group, update_nnps=True))
group = []
for fluid in self.fluids:
group.append(
SummationDensity(dest=fluid,
sources=self.fluids,
dim=self.dim))
equations.append(Group(equations=group, update_nnps=False))
group = []
for fluid in self.fluids:
group.append(
UpdateSmoothingLengthFromVolume(dest=fluid,
sources=None,
k=self.kernel_factor,
dim=self.dim))
equations.append(Group(equations=group, update_nnps=True))
group = []
for fluid in self.fluids:
group.append(
SummationDensity(dest=fluid,
sources=self.fluids,
dim=self.dim))
equations.append(Group(equations=group, update_nnps=False))
# Done with finding the optimal 'h'
g2 = []
for fluid in self.fluids:
g2.append(IdealGasEOS(dest=fluid, sources=None, gamma=self.gamma))
equations.append(Group(equations=g2))
g3 = []
for fluid in self.fluids:
g3.append(
MPMAccelerations(dest=fluid,
sources=self.fluids,
alpha1_min=self.alpha1,
alpha2_min=self.alpha2,
beta=self.beta,
update_alpha1=self.update_alpha1,
update_alpha2=self.update_alpha2))
equations.append(Group(equations=g3))
return equations
def get_surface_tension_equations(fluids, solids, scheme, rho0, p0, c0, b,
factor1, factor2, nu, sigma, d, epsilon,
gamma, real=False):
"""
This function returns the required equations for the multiphase
formulation taking inputs of the fluid particles array, solid particles
array, the scheme to be used and other physical parameters
Parameters
------------------
fluids: list
List of names of fluid particle arrays
solids: list
List of names of solid particle arrays
scheme: string
The scheme with which the equations are to be setup.
Supported Schemes:
1. TVF scheme with Morris' surface tension.
String to be used: "tvf"
2. Adami's surface tension implementation which doesn't involve
calculation of curvature. String to be used: "adami_stress"
3. Adami's surface tension implementation which involves
calculation of curvature. String to be used: "adami"
4. Shadloo Yildiz surface tension formulation.
String to be used: "shadloo"
5. Morris' surface tension formulation. This is the default scheme
which will be used if none of the above strings are input as
scheme.
rho0 : float
The reference density of the medium (Currently multiple reference
densities for different particles is not supported)
p0 : float
The background pressure of the medium(Currently multiple background
pressures for different particles is not supported)
c0 : float
The speed of sound of the medium(Currently multiple speeds of sounds
for different particles is not supported)
b : float
The b parameter of the generalized Tait Equation of State. Refer to
the Tait Equation's documentation for reference
factor1 : float
The factor for scaling of smoothing length for calculation of
interface curvature number for shadloo's scheme
factor2 : float
The factor for scaling back of smoothing length for calculation of
forces after calculating the interface curvature number in shadloo's
scheme
nu : float
The kinematic viscosity of the medium
sigma : float
The surface tension of the system
d : int
The number of dimensions of the problem in the cartesian space
epsilon: float
Put this option false if the equations are supposed to be evaluated
for the ghost particles, else keep it True
"""
if scheme == 'tvf':
result = []
equations = []
for i in fluids+solids:
equations.append(SummationDensity(dest=i, sources=fluids+solids))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(StateEquation(dest=i, sources=None, rho0=rho0,
p0=p0))
equations.append(SmoothedColor(dest=i, sources=fluids+solids))
for i in solids:
equations.append(SolidWallPressureBCnoDensity(dest=i,
sources=fluids))
equations.append(SmoothedColor(dest=i, sources=fluids+solids))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(MorrisColorGradient(dest=i, sources=fluids+solids,
epsilon=epsilon))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(InterfaceCurvatureFromNumberDensity(
dest=i, sources=fluids+solids, with_morris_correction=True))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(MomentumEquationPressureGradient(dest=i,
sources=fluids+solids, pb=p0))
equations.append(MomentumEquationViscosity(dest=i, sources=fluids,
nu=nu))
equations.append(CSFSurfaceTensionForce(dest=i, sources=None,
sigma=sigma))
equations.append(MomentumEquationArtificialStress(dest=i,
sources=fluids))
if len(solids) != 0:
equations.append(SolidWallNoSlipBC(dest=i, sources=solids,
nu=nu))
result.append(Group(equations))
elif scheme == 'adami_stress':
result = []
equations = []
for i in fluids+solids:
equations.append(SummationDensity(dest=i, sources=fluids+solids))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(TaitEOS(dest=i, sources=None, rho0=rho0, c0=c0,
gamma=gamma, p0=p0))
for i in solids:
equations.append(SolidWallPressureBCnoDensity(dest=i,
sources=fluids))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(ColorGradientAdami(dest=i, sources=fluids+solids))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(ConstructStressMatrix(dest=i, sources=None,
sigma=sigma, d=d))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(MomentumEquationPressureGradientAdami(dest=i,
sources=fluids+solids))
equations.append(MomentumEquationViscosityAdami(dest=i,
sources=fluids))
equations.append(SurfaceForceAdami(dest=i, sources=fluids+solids))
if len(solids) != 0:
equations.append(SolidWallNoSlipBC(dest=i, sources=solids,
nu=nu))
result.append(Group(equations))
elif scheme == 'adami':
result = []
equations = []
for i in fluids+solids:
equations.append(SummationDensity(dest=i, sources=fluids+solids))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(StateEquation(dest=i, sources=None, rho0=rho0,
p0=p0, b=b))
for i in solids:
equations.append(SolidWallPressureBCnoDensity(dest=i,
sources=fluids))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(AdamiColorGradient(dest=i, sources=fluids+solids))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(AdamiReproducingDivergence(dest=i,
sources=fluids+solids,
dim=d))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(MomentumEquationPressureGradient(
dest=i, sources=fluids+solids, pb=0.0))
equations.append(MomentumEquationViscosityAdami(dest=i,
sources=fluids))
equations.append(CSFSurfaceTensionForceAdami(dest=i, sources=None))
if len(solids) != 0:
equations.append(SolidWallNoSlipBC(dest=i, sources=solids,
nu=nu))
result.append(Group(equations))
elif scheme == 'shadloo':
result = []
equations = []
for i in fluids+solids:
equations.append(SummationDensity(dest=i, sources=fluids+solids))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(StateEquation(dest=i, sources=None, rho0=rho0,
p0=p0, b=b))
equations.append(SY11ColorGradient(dest=i, sources=fluids+solids))
for i in solids:
equations.append(SolidWallPressureBCnoDensity(dest=i,
sources=fluids))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(ScaleSmoothingLength(dest=i, sources=None,
factor=factor1))
result.append(Group(equations, real=real, update_nnps=True))
equations = []
for i in fluids:
equations.append(SY11DiracDelta(dest=i, sources=fluids+solids))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(InterfaceCurvatureFromNumberDensity(
dest=i, sources=fluids+solids, with_morris_correction=True))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(ScaleSmoothingLength(dest=i, sources=None,
factor=factor2))
result.append(Group(equations, real=real, update_nnps=True))
equations = []
for i in fluids:
equations.append(MomentumEquationPressureGradient(
dest=i, sources=fluids+solids, pb=0.0))
equations.append(MomentumEquationViscosity(dest=i, sources=fluids,
nu=nu))
equations.append(ShadlooYildizSurfaceTensionForce(dest=i,
sources=None,
sigma=sigma))
if len(solids) != 0:
equations.append(SolidWallNoSlipBC(dest=i, sources=solids,
nu=nu))
result.append(Group(equations))
else:
result = []
equations = []
for i in fluids+solids:
equations.append(SummationDensitySourceMass(dest=i,
sources=fluids+solids))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(TaitEOS(dest=i, sources=None, rho0=rho0, c0=c0,
gamma=gamma, p0=0.0))
equations.append(SmoothedColor(dest=i, sources=fluids+solids))
for i in solids:
equations.append(SolidWallPressureBCnoDensity(dest=i,
sources=fluids))
equations.append(SmoothedColor(dest=i, sources=fluids+solids))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(MorrisColorGradient(dest=i, sources=fluids+solids,
epsilon=epsilon))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(InterfaceCurvatureFromDensity(
dest=i, sources=fluids+solids, with_morris_correction=True))
result.append(Group(equations, real=real))
equations = []
for i in fluids:
equations.append(MomentumEquationPressureGradientMorris(dest=i,
sources=fluids+solids))
equations.append(MomentumEquationViscosityMorris(dest=i,
sources=fluids))
equations.append(CSFSurfaceTensionForce(dest=i, sources=None,
sigma=sigma))
if len(solids) != 0:
equations.append(SolidWallNoSlipBC(dest=i, sources=solids,
nu=nu))
result.append(Group(equations))
return result
def create_equations(self):
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']),
]),
# Given the updated number density for the fluid, we can update
# the fluid pressure. 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),
SmoothedColor(dest='fluid', sources=['fluid']),
]),
#################################################################
# Begin Surface tension formulation
#################################################################
# Scale the smoothing lengths to determine the interface
# quantities.
Group(equations=[
ScaleSmoothingLength(dest='fluid',
sources=None,
factor=factor1)
],
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=[
MorrisColorGradient(dest='fluid',
sources=['fluid'],
epsilon=0.01 / h0),
# ColorGradientUsingNumberDensity(dest='fluid',sources=['fluid'],
# epsilon=epsilon),
# AdamiColorGradient(dest='fluid', sources=['fluid']),
], ),
# 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),
# AdamiReproducingDivergence(dest='fluid',sources=['fluid'],
# dim=2),
], ),
# Now rescale the smoothing length to the original value for the
# rest of the computations.
Group(
equations=[
ScaleSmoothingLength(dest='fluid',
sources=None,
factor=factor2)
],
update_nnps=False,
),
#################################################################
# End Surface tension formulation
#################################################################
# The main acceleration block
Group(
equations=[
# Gradient of pressure for the fluid phase using the
# number density formulation.
MomentumEquationPressureGradient(dest='fluid',
sources=['fluid'],
pb=p0),
# Artificial viscosity for the fluid phase.
MomentumEquationViscosity(dest='fluid',
sources=['fluid'],
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 equations
def create_equations(self):
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 compute the gradient of the
# color function with respect to the original smoothing
# length. This will compute the interface normals. Also compute
# the smoothed color based on the color index for a particle.
Group(equations=[
IsothermalEOS(
dest='fluid', sources=None, rho0=rho0, c0=c0, p0=p0),
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']),
], ),
# Compute the interface curvature using the modified smoothing
# length and interface normals computed in the previous Group.
Group(equations=[
InterfaceCurvatureFromNumberDensity(dest='fluid',
sources=['fluid']),
], ),
# 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,
b=1.0),
], ),
# The main acceleration block
Group(
equations=[
# Body force due to gravity
BodyForce(dest='fluid', sources=None, fy=gy),
# Gradient of pressure for the fluid phase using the
# number density formulation. The no-penetration boundary
# condition is taken care of by using the boundary
# pressure and density.
PressureGradientUsingNumberDensity(
dest='fluid', sources=['fluid', 'wall']),
# Artificial viscosity for the fluid phase.
ClearyArtificialViscosity(dest='fluid',
sources=['fluid', 'wall'],
dim=dim,
alpha=alpha),
# Surface tension force for the SY11 formulation
ShadlooYildizSurfaceTensionForce(dest='fluid',
sources=None,
sigma=sigma),
# XSPH Correction
XSPHCorrection(dest='fluid', sources=['fluid'], eps=0.1),
], )
]
return equations
def create_equations(self):
sy11_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'])]),
# Given the updated number density for the fluid, we can update
# the fluid pressure. Additionally, we can compute the Shepard
# Filtered velocity required for the no-penetration boundary
# condition. Also compute the gradient of the color function to
# compute the normal at the interface.
Group(equations=[
StateEquation(dest='fluid', sources=None, rho0=rho0, p0=p0),
SY11ColorGradient(dest='fluid', sources=['fluid'])
]),
#################################################################
# Begin Surface tension formulation
#################################################################
# Scale the smoothing lengths to determine the interface
# quantities.
Group(equations=[
ScaleSmoothingLength(dest='fluid',
sources=None,
factor=factor1)
],
update_nnps=False),
# Compute the discretized dirac delta with respect to the new
# smoothing length.
Group(equations=[SY11DiracDelta(dest='fluid',
sources=['fluid'])], ),
# 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=factor2)
],
update_nnps=False,
),
#################################################################
# End Surface tension formulation
#################################################################
# 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'],
pb=p0),
# Artificial viscosity for the fluid phase.
MomentumEquationViscosity(dest='fluid',
sources=['fluid'],
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']),
], )
]
morris_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'])]),
# Given the updated number density for the fluid, we can update
# the fluid pressure. Additionally, we can compute the Shepard
# Filtered velocity required for the no-penetration 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),
SmoothedColor(dest='fluid', sources=['fluid'], smooth=True),
]),
#################################################################
# Begin Surface tension formulation
#################################################################
# Compute the gradient of the smoothed color field. 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=[
MorrisColorGradient(dest='fluid',
sources=['fluid'],
epsilon=epsilon),
], ),
# Compute the interface curvature computed in the previous Group.
Group(equations=[
InterfaceCurvatureFromNumberDensity(
dest='fluid',
sources=['fluid'],
with_morris_correction=True),
], ),
#################################################################
# End Surface tension formulation
#################################################################
# The main acceleration block
Group(
equations=[
# Gradient of pressure for the fluid phase
MomentumEquationPressureGradient(dest='fluid',
sources=['fluid'],
pb=p0),
# Artificial viscosity for the fluid phase.
MomentumEquationViscosity(dest='fluid',
sources=['fluid'],
nu=nu),
# Surface tension force for the Morris formulation
CSFSurfaceTensionForce(dest='fluid',
sources=None,
sigma=sigma),
# Artificial stress for the fluid phase
MomentumEquationArtificialStress(dest='fluid',
sources=['fluid']),
], )
]
adami_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'])]),
# Given the updated number density for the fluid, we can update
# the fluid pressure. Additionally, we can compute the Shepard
# Filtered velocity required for the no-penetration boundary
# condition.
Group(equations=[
StateEquation(dest='fluid', sources=None, rho0=rho0, p0=p0),
]),
#################################################################
# Begin Surface tension formulation
#################################################################
# Compute the gradient of the color field.
Group(equations=[
AdamiColorGradient(dest='fluid', sources=['fluid']),
], ),
# Compute the interface curvature using the color gradients
# computed in the previous Group.
Group(equations=[
AdamiReproducingDivergence(dest='fluid',
sources=['fluid'],
dim=2),
], ),
#################################################################
# End Surface tension formulation
#################################################################
# The main acceleration block
Group(
equations=[
# Gradient of pressure for the fluid phase
MomentumEquationPressureGradient(dest='fluid',
sources=['fluid'],
pb=p0),
# Artificial viscosity for the fluid phase.
MomentumEquationViscosity(dest='fluid',
sources=['fluid'],
nu=nu),
# Surface tension force for the CSF formulation
CSFSurfaceTensionForce(dest='fluid',
sources=None,
sigma=sigma),
# Artificial stress for the fluid phase
MomentumEquationArtificialStress(dest='fluid',
sources=['fluid']),
], )
]
if self.options.scheme == 'morris':
return morris_equations
elif self.options.scheme == 'adami':
return adami_equations
else:
return sy11_equations
def create_equations(self):
sy11_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']),
# SummationDensity(dest='wall', sources=['fluid', 'wall'])
],
real=False),
# Given the updated number density for the fluid, we can update
# the fluid pressure. Additionally, we can compute the Shepard
# Filtered velocity required for the no-penetration boundary
# condition. Also compute the gradient of the color function to
# compute the normal at the interface.
Group(
equations=[
StateEquation(dest='fluid',
sources=None,
rho0=rho0,
b=0.0,
p0=p0),
SetWallVelocity(dest='wall', sources=['fluid']),
# SmoothedColor(dest='fluid', sources=['fluid']),
],
real=False),
Group(equations=[
SolidWallPressureBC(dest='wall',
sources=['fluid'],
p0=p0,
rho0=rho0,
gy=gy,
b=1.0),
],
real=False),
#################################################################
# Begin Surface tension formulation
#################################################################
# Scale the smoothing lengths to determine the interface
# quantities.
Group(equations=[
ScaleSmoothingLength(dest='fluid',
sources=None,
factor=factor1)
],
update_nnps=True),
# Compute the discretized dirac delta with respect to the new
# smoothing length.
Group(equations=[
SY11DiracDelta(dest='fluid', sources=['fluid', 'wall'])
],
real=False),
# Compute the interface curvature using the modified smoothing
# length and interface normals computed in the previous Group.
Group(equations=[
InterfaceCurvatureFromNumberDensity(dest='fluid',
sources=['fluid']),
],
real=False),
# Now rescale the smoothing length to the original value for the
# rest of the computations.
Group(equations=[
ScaleSmoothingLength(dest='fluid',
sources=None,
factor=factor2)
],
update_nnps=True),
#################################################################
# End Surface tension formulation
#################################################################
# 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.
BodyForce(dest='fluid', sources=None, fy=gy),
MomentumEquationPressureGradient(dest='fluid',
sources=['fluid',
'wall']),
# Artificial viscosity for the fluid phase.
ShadlooArtificialViscosity(dest='fluid',
sources=['fluid', 'wall']),
# Surface tension force for the SY11 formulation
ShadlooYildizSurfaceTensionForce(dest='fluid',
sources=None,
sigma=sigma),
], )
]
return sy11_equations