Runtime Parameters Documentation for FLASH Release 4.6.1


physics/Gravity
    grav_boundary_type [STRING] ["isolated"]
        Valid Values: Unconstrained
        Type of gravitational boundary condition if a Poisson solve is used for
        Gravity; string-valued version of grav_boundary. Accepts: "isolated",
        "periodic", "dirichlet", and maybe others, depending on the Poisson
        solver used. This is declared in the stub level of the Gravity unit to
        allow the Grid unit to refer to this runtime parameter even when no
        Gravity implementation is included.
    useGravity [BOOLEAN] [FALSE]
        Whether gravity calculations should be performed.

physics/Gravity/GravityMain
    useGravity [BOOLEAN] [TRUE]
        Should the gravity calculations be performed?

physics/Gravity/GravityMain/Constant
    gconst [REAL] [-981.]
        Valid Values: Unconstrained
        Gravitational acceleration constant
    gdirec [STRING] ["x"]
        Valid Values: Unconstrained
        Direction of acceleration ("x", "y", "z")

physics/Gravity/GravityMain/PlanePar
    gravsoft [REAL] [.0001]
        Valid Values: Unconstrained
        softening length
    ptdirn [INTEGER] [1]
        Valid Values: Unconstrained
        x = 1, y = 2, z = 3
    ptmass [REAL] [10000.]
        Valid Values: Unconstrained
        mass of the point
    ptxpos [REAL] [1.]
        Valid Values: Unconstrained
        location of the point mass, in the ptdirn direction

physics/Gravity/GravityMain/PointMass
    gravsoft [REAL] [0.001]
        Valid Values: Unconstrained

    ptmass [REAL] [10000.]
        Valid Values: Unconstrained

    ptxpos [REAL] [1.]
        Valid Values: Unconstrained

    ptypos [REAL] [-10.]
        Valid Values: Unconstrained

    ptzpos [REAL] [0.]
        Valid Values: Unconstrained


physics/Gravity/GravityMain/Poisson
    grav_temporal_extrp [BOOLEAN] [FALSE]
        extrapolate or otherwise rescale
    grav_unjunkPden [BOOLEAN] [TRUE]
        controls whether Gravity_potentialListOfBlocks attempts to restore the
        part of the "pden" ("particle density") UNK variable that is due to
        particles, or leaves "pden" as it is, after a Poisson equation solve.
        This only applies meaningfully when a "pden" variable is declared and
        the gravitational potential is calculated by solving a Poisson equation
        whose right-hand side includes a mass distribution to which both
        hydrodynamic fluid density and massive particles contribute. The "pden"
        variable will have been set to the sum of the fluid density ("dens"
        variable) and the density resulting from mapping massive particles to
        the mesh, so that is what remains in "pden" when grav_unjunkPden is set
        to FALSE. Otherwise, "dens" will be subtraced from "pden" before
        Gravity_potentialListOfBlocks returns, and "pden" will be left
        containing only the mass density that is due to particles.
    point_mass [REAL] [0.e0]
        Valid Values: Unconstrained
        mass of the central point-like object
    point_mass_rsoft [REAL] [0.e0]
        Valid Values: Unconstrained
        softening radius for the point-like mass (in units of number of the
        finest level cells)
    updateGravity [BOOLEAN] [TRUE]
        allow gravity value to be updated

physics/Gravity/GravityMain/Poisson/BHTree
    grav_boundary_type [STRING] ["mixed"]
        Valid Values: "isolated", "periodic", "mixed"

    grav_boundary_type_x [STRING] ["isolated"]
        Valid Values: "isolated", "periodic"
        Gravity boundary type for the X direction, used if grav_boundary_type ==
        "mixed"
    grav_boundary_type_y [STRING] ["isolated"]
        Valid Values: "isolated", "periodic"
        Gravity boundary type for the Y direction, used if grav_boundary_type ==
        "mixed"
    grav_boundary_type_z [STRING] ["isolated"]
        Valid Values: "isolated", "periodic"
        Gravity boundary type for the Z direction, used if grav_boundary_type ==
        "mixed"
    grv_bhAccErr [REAL] [0.1]
        Valid Values: 0 to INFTY
        Maximum allowed error (either relative or absolute depending on value of
        grv_bhUseRelAccErr) for the MAC.
    grv_bhEwaldAlwaysGenerate [BOOLEAN] [TRUE]
        If set TRUE the Ewald field will be always re-generated even if the file
        with it exists.
    grv_bhEwaldFName [STRING] ["ewald_coeffs"]
        Valid Values: Unconstrained
        File with coefficients of the Ewald field Taylor series expansion.
    grv_bhEwaldFNameAccV42 [STRING] ["ewald_field_acc"]
        Valid Values: Unconstrained
        File to store the Ewald field for the acceleration.
    grv_bhEwaldFNamePotV42 [STRING] ["ewald_field_pot"]
        Valid Values: Unconstrained
        File to store the Ewald field for the potential.
    grv_bhEwaldFieldNxV42 [INTEGER] [32]
        Valid Values: 1 to INFTY
        Number of points of the Ewald field in the x-direction.
    grv_bhEwaldFieldNyV42 [INTEGER] [32]
        Valid Values: 1 to INFTY
        Number of points of the Ewald field in the x-direction.
    grv_bhEwaldFieldNzV42 [INTEGER] [32]
        Valid Values: 1 to INFTY
        Number of points of the Ewald field in the x-direction.
    grv_bhEwaldNPer [INTEGER] [32]
        Valid Values: Unconstrained
        corresponds to th number of points+1 of the Taylor expansion in (one of)
        periodic direction(s)
    grv_bhEwaldNRefV42 [INTEGER] [-1]
        Valid Values: Unconstrained
        Number of refinement levels of the Ewald field. If negative, it is
        calculated automatically from the minimum cell size.
    grv_bhEwaldSeriesN [INTEGER] [10]
        Valid Values: Unconstrained
        Number of terms used in expansion to calculate the Ewald field.
    grv_bhExtrnPotCenterX [REAL] [0.0]
        Valid Values: Unconstrained
        X-coordinate of the center of the external potention.
    grv_bhExtrnPotCenterY [REAL] [0.0]
        Valid Values: Unconstrained
        Y-coordinate of the center of the external potention.
    grv_bhExtrnPotCenterZ [REAL] [0.0]
        Valid Values: Unconstrained
        Z-coordinate of the center of the external potention.
    grv_bhExtrnPotFile [STRING] ["external_potential.dat"]
        Valid Values: Unconstrained
        File including the external background potential.
    grv_bhExtrnPotType [STRING] ["planez"]
        Valid Values: "spherical", "planez"
        Type of the external potential (spherical or plane-parallel).
    grv_bhLinearInterpolOnlyV42 [BOOLEAN] [TRUE]
        If set TRUE, only the linear interpolation in the Ewald field is used.
        Otherwise, more expensive and accurate quadratic interpolation is used
        in some cases.
    grv_bhMAC [STRING] ["ApproxPartialErr"]
        Valid Values: "ApproxPartialErr", "MaxPartialErr", "SumSquare"
        Type of the Multipole Acceptace Criterion (MAC) used during the tree
        walk.
    grv_bhMPDegree [INTEGER] [2]
        Valid Values: 2, 3, 4
        Degree of multipole expansion used to estimate the error of a single
        node contribution if the "ApproxPartErro" MAC is used. Recently, only
        value 2 makes sense, because quadrupole and higher order moments are not
        stored in tree nodes.
    grv_bhNewton [REAL] [-1.0]
        Valid Values: -INFTY to INFTY
        Value for Newton's constant. Specify -1.0 to use the value from the
        PhysicalConstants code unit.
    grv_bhUseRelAccErr [BOOLEAN] [FALSE]
        If set to TRUE, parameter grv_bhAccErr has meaning of the relative error
        in acceleration. Otherwise, it is an absolute error.
    grv_useExternalPotential [BOOLEAN] [FALSE]

    grv_usePoissonPotential [BOOLEAN] [TRUE]