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]

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