Beispiel #1
0
    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
Beispiel #2
0
    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
Beispiel #4
0
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
Beispiel #5
0
    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
Beispiel #6
0
    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
Beispiel #7
0
    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
Beispiel #8
0
    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