Back to Input Deck Cards

GRID

Specifies the discretization scheme to be employed in the simulation.

Required Cards:

TYPE <type>

Grid type. Options: STRUCTURED, UNSTRUCTURED, UNSTRUCTURED_EXPLICIT

  • STRUCTURED

    • CARTESIAN (default)

    • CYLINDRICAL

    • SPHERICAL

  • UNSTRUCTURED <filename>

    Standard finite element format where cells (elements) are defined by lists of vertices and vertices are defined by coordinates. We often refer to these as implicit unstructured grids. See PFLOTRAN_cell_numbering_schemes.pdf for cell face and vertex numbering schemes.

  • UNSTRUCTURED_EXPLICIT <filename>

    The grid is defined by a list of cells and connectivity. Cells are defined by an id, coordinate and volume while connections are composed of two cell ids, an area and a face-center coordinate.

NXYZ <int int int>

# of cells in x, y, z dimensions (structured only)

BOUNDS (may not be used with DXYZ)
Specifies bounds of structured Cartesian grid (see examples below)
BOUNDS
  x_min y_min z_min
  x_max y_max z_max
/
Notes:

  1. The origin is automatically calculated based on the lower bound.

  2. Cylindrical grids include only two values per line (for x and z) while spherical grids include only one.

DXYZ (may not be used with BOUNDS)
Specifies grid spacing of structured Cartesian grid (see examples below).
DXYZ
  dx
  dy
  dz
/
Notes:

  1. For each dimension, enter a single value (which is applied to all cells in the respective dimension) or multiple values (equal to the number of cells in the respective dimension; e.g. NX values).

  2. Use line continuation through a backslash ‘' when lines exceed ~80 characters (see DXYZ examples below). PFLOTRAN input can handle lines of 512 characters, but that may change.

FILE <filename>

Name of file containing grid information (unstructured only)

Optional Cards:

GRAVITY <float float float>

Specifies directional gravity vector. Default = <0,0,-9.8068>

ORIGIN <float float float>

Coordinate of grid origin. Required with DXYZ should the origin not lie at <0,0,0>. Default = <0,0,0>

INVERT_Z

Inverts the z axis (positive Z is down instead of default up)

PERM_TENSOR_TO_SCALAR_MODEL <string>

Specifies the algorithm for converting the diagonal permeability tensor to a scalar at a face for a flux calculation. Options include [LINEAR, FLOW, POTENTIAL, FLOW_FULL_TENSOR]. _FULL_TENSOR option enable flow simulation considering off-diagonal permeability components which occur when permeability principal directions are not aligned with the grid xyz axis. Defaults: LINEAR for structured grids, and POTENTIAL for unstructured grids.

MAX_CELLS_SHARING_A_VERTEX <int>

Specifies the maximum number of cells sharing a single vertex. Necessary for expanding arrays used to read in complex grids where a vertex is shared by a large number of cells. Default = 24

STENCIL_WIDTH <int>

Width of structured grid stencil. Default = 1

STENCIL_TYPE <string>

Specifies stencil with options BOX or STAR. Default = STAR

IMPLICIT_GRID_AREA_CALCULATION <string>

Specifies whether or not project the face area in the direction of the vector connecting the two cells sharing the face with option TRUE_AREA or PROJECTED_AREA for implicit UNSTRUCTURED grid. Default = PROJECTED_AREA

DOMAIN_FILENAME <string>

Specifies the path to the filename defining explicit unstructured grid geometry for inclusion in HDF5 output enabling plotting in Paraview/Visit.

UPWIND_FRACTION_METHOD <string>

Specifies the approach used to calculate the upwind fraction for UNSTRUCTURED_EXPLICIT grids. Options include [FACE_CENTER_PROJECTION (default), CELL_VOLUME, ABSOLUTE_DISTANCE].

2ND_ORDER_BOUNDARY_CONDITION

A simple approach to boundary ghost cells. Specifies that boundary conditions be applied a full cell width away from the cell center instead of a half cell width (at the face). Only supported for structured grids.

Examples

GRID
  TYPE structured
  NXYZ 5 4 2
  DXYZ
    2@1. 3@1.5
    1@1. 3@0.5
    2@0.25
  /
END

GRID
  TYPE structured
  NXYZ 5 4 2
  BOUNDS
    0. 0. 0.
    100. 50. 25.
  /
END

BOUNDS card with GRID

BOUNDS
 0. 0. 0.
 100. 50. 25.
/

DXYZ card with GRID

DXYZ
  1.
  1.
  0.25
/

DXYZ
  2@1. 3@1.5
  1@1. 3@0.5
  2@0.25
/

DXYZ with continuation:

NXYZ 130 1 9
DXYZ
  0.08 0.09 0.10 0.10 0.12 0.13 0.14 0.15 0.17 0.19 \
  0.20 0.22 0.25 0.27 0.30 0.33 0.36 0.40 0.44 0.48 \
  0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 \
  0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 \
  0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 \
  0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 \
  0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 \
  0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 \
  0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 \
  0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.53 \
  0.53 0.53 0.53 0.53 0.53 0.53 0.53 0.64 0.76 0.92 \
  1.10 1.32 1.58 1.90 2.28 2.73 3.28 3.94 4.73 5.67 \
  6.80 8.17 9.80 11.76 14.11 16.93 20.32 24.38 29.26 35.11
  1
  1.666666666666666666667 ! note that all 9 cells in z will be assign 1.666...7.
/

Cylindrical Coordinates

Note: For cylindrical coordinates, the X dimension corresponds to the radius of the cylinder while the Z dimension represents the height. It is assumed that the Y dimension is variable with NY = 1, and no Y grid spacing is specified. PFLOTRAN will calculate the distance in the Y direction automatically based on the cylindrical coordinate system.

GRID
  TYPE structured cylindrical
  NXYZ 100 1 10
  BOUNDS
    0.d0 0.
    100.d0 10.d0
  /
END

But all REGIONs must include Y coordinates of 0 and 1. E.g.

REGION all
  COORDINATES
    0.d0 0.d0 0.d0
    100.d0 1.d0 10.d0
  /
END

REGION top
  FACE top
  COORDINATES
    0.d0 0.d0 10.d0
    100.d0 1.d0 10.d0
  /
END

Unstructured Grid Examples

Format

Example implicit unstructured grid (see mixed.ugi)

15 24
P 4 5 6 2 1
T 4 3 5 1
W 2 7 6 4 9 5
W 8 7 2 10 9 4
W 10 9 4 21 14 11
H 19 9 5 12 17 7 6 16
T 5 13 14 15
T 5 14 9 15
P 5 9 19 12 15
P 13 5 12 22 15
H 20 10 9 19 18 8 7 17
H 24 21 14 23 20 10 9 19
P 23 19 9 14 15
P 22 12 19 23 15
P 22 23 14 13 15
5.000000e+00 5.000000e+00 5.000000e+00
5.000000e+00 2.500000e+00 5.000000e+00
5.000000e+00 5.000000e+00 2.500000e+00
5.000000e+00 2.500000e+00 2.500000e+00
2.500000e+00 5.000000e+00 2.500000e+00
2.500000e+00 5.000000e+00 5.000000e+00
2.500000e+00 2.500000e+00 5.000000e+00
2.500000e+00 0.000000e+00 5.000000e+00
2.500000e+00 2.500000e+00 2.500000e+00
2.500000e+00 0.000000e+00 2.500000e+00
5.000000e+00 2.500000e+00 0.000000e+00
0.000000e+00 5.000000e+00 2.500000e+00
2.500000e+00 5.000000e+00 0.000000e+00
2.500000e+00 2.500000e+00 0.000000e+00
1.250000e+00 3.750000e+00 1.250000e+00
0.000000e+00 5.000000e+00 5.000000e+00
0.000000e+00 2.500000e+00 5.000000e+00
0.000000e+00 0.000000e+00 5.000000e+00
0.000000e+00 2.500000e+00 2.500000e+00
0.000000e+00 0.000000e+00 2.500000e+00
2.500000e+00 0.000000e+00 0.000000e+00
0.000000e+00 5.000000e+00 0.000000e+00
0.000000e+00 2.500000e+00 0.000000e+00
0.000000e+00 0.000000e+00 0.000000e+00