def create_equations(self):
morris_equations = [
Group(equations=[
SummationDensitySourceMass(
dest='fluid', sources=[
'fluid', 'wall']),
SummationDensitySourceMass(
dest='wall', sources=[
'fluid', 'wall']),
]),
Group(equations=[
TaitEOS(dest='fluid', sources=None, rho0=rho0, c0=c0, gamma=1, p0=0.0),
SolidWallPressureBCnoDensity(dest='wall', sources=['fluid']),
SmoothedColor(
dest='fluid', sources=[
'fluid', 'wall']),
SmoothedColor(
dest='wall', sources=[
'fluid', 'wall']),
]),
Group(equations=[
MorrisColorGradient(dest='fluid', sources=['fluid', 'wall'],
epsilon=epsilon),
]),
Group(equations=[
InterfaceCurvatureFromDensity(dest='fluid', sources=['fluid', 'wall'],
with_morris_correction=True),
]),
Group(
equations=[
# MomentumEquation(dest='fluid', sources=['fluid', 'wall'], c0=c0, tensile_correction=False, alpha=0.0, beta=0.0),
MomentumEquationPressureGradientMorris(dest='fluid', sources=['fluid', 'wall']),
MomentumEquationViscosityMorris(dest='fluid', sources=['fluid']),
CSFSurfaceTensionForce(
dest='fluid', sources=None, sigma=sigma),
SolidWallNoSlipBC(dest='fluid', sources=['wall'], nu=nu0)
]),
]
return morris_equations
def create_equations(self):
morris_equations = [
Group(equations=[
SummationDensitySourceMass(dest='fluid',
sources=['fluid', 'wall']),
SummationDensitySourceMass(dest='wall',
sources=['fluid', 'wall']),
]),
Group(equations=[
TaitEOS(dest='fluid',
sources=None,
rho0=rho1,
c0=c0,
gamma=1,
p0=p1),
SolidWallPressureBCnoDensity(
dest='wall', sources=['fluid'], rho0=rho1, p0=p1),
SmoothedColor(dest='fluid', sources=['fluid', 'wall']),
SmoothedColor(dest='wall', sources=['fluid', 'wall']),
]),
Group(equations=[
MorrisColorGradient(
dest='fluid', sources=['fluid', 'wall'], epsilon=epsilon),
]),
Group(equations=[
FindMaxddelta(dest='fluid', sources=None),
]),
Group(equations=[
MomentumEquationPressureGradientMorris(
dest='fluid', sources=['fluid', 'wall']),
MomentumEquationViscosityMorris(dest='fluid',
sources=['fluid']),
CSFSurfaceTensionForce(
dest='fluid', sources=['fluid', 'wall'], sigma=sigma),
SolidWallNoSlipBC(dest='fluid', sources=['wall'], nu=nu0)
]),
]
return morris_equations
def create_equations(self):
morris_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']),
], )
]
return morris_equations
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 create_equations(self):
morris_equations = [
Group(equations=[
SummationDensity(dest='fluid', sources=['fluid']),
],
real=False,
update_nnps=False),
Group(
equations=[
# IsothermalEOS(
# dest='fluid',
# sources=None,
# rho0=rho1,
# p0=0.0,
# c0=c0),
TaitEOS(dest='fluid',
sources=None,
rho0=rho1,
c0=c0,
gamma=1.0,
p0=p1),
SmoothedColor(dest='fluid', sources=[
'fluid',
]),
# ScaleSmoothingLength(dest='fluid', sources=None, factor=2.0/3.0),
],
real=True,
update_nnps=True),
Group(
equations=[
MorrisColorGradient(dest='fluid',
sources=[
'fluid',
],
epsilon=epsilon),
# ScaleSmoothingLength(dest='fluid', sources=None, factor=1.5),
],
real=False,
update_nnps=False),
# Group(equations=[
# InterfaceCurvatureFromNumberDensity(dest='fluid', sources=['fluid'],
# with_morris_correction=True),
# ], real=False, update_nnps=False),
Group(equations=[
FindMaxddelta(dest='fluid', sources=None),
]),
Group(equations=[
MomentumEquationPressureGradient(dest='fluid',
sources=['fluid']),
MomentumEquationViscosity(dest='fluid', sources=['fluid']),
],
real=False,
update_nnps=False),
Group(equations=[
CSFSurfaceTensionForce(dest='fluid', sources=['fluid']),
],
real=False,
update_nnps=False)
]
return morris_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']),
]),
# 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