Runtime Parameters Documentation for FLASH Release 4.2

    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.

    useGravity [BOOLEAN] [TRUE]
        Should the gravity calculations be performed?

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

    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

    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

    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

    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 ==
    grav_boundary_type_y [STRING] ["isolated"]
        Valid Values: "isolated", "periodic"
        Gravity boundary type for the Y direction, used if grav_boundary_type ==
    grav_boundary_type_z [STRING] ["isolated"]
        Valid Values: "isolated", "periodic"
        Gravity boundary type for the Z direction, used if grav_boundary_type ==
    grv_bhAccErr [REAL] [0.1]
        Valid Values: 0 to INFTY

    grv_bhEwaldAlwaysGenerate [BOOLEAN] [TRUE]

    grv_bhEwaldFName [STRING] ["ewald_field"]
        Valid Values: Unconstrained

    grv_bhEwaldFieldNx [INTEGER] [32]
        Valid Values: 1 to INFTY

    grv_bhEwaldFieldNy [INTEGER] [32]
        Valid Values: 1 to INFTY

    grv_bhEwaldFieldNz [INTEGER] [32]
        Valid Values: 1 to INFTY

    grv_bhEwaldNRef [INTEGER] [-1]
        Valid Values: Unconstrained

    grv_bhEwaldSeriesN [INTEGER] [10]
        Valid Values: Unconstrained

    grv_bhLinearInterpolOnly [BOOLEAN] [TRUE]

    grv_bhMAC [STRING] ["ApproxPartialErr"]
        Valid Values: "ApproxPartialErr", "MaxPartialErr", "SumSquare"

    grv_bhMPDegree [INTEGER] [2]
        Valid Values: 2, 3, 4

    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]