2D Grid Files

Two-dimensional grids are stored in 2D grid files. The grids can be either cell-centered or mesh-centered. If the grid is mesh-centered, a set of material IDs may be included in the file. The 2D grid file format is shown in Figure 1, and a sample file in Figure 2.

GRID2D

/* File type */

TYPE i

/* Type of grid. Mesh or Cell centered. */

IJ ±idir ±jdir

/* Card for defining rows, columns. */

DIM nx ny

/* # of cell boundaries in each direction. */

x1

/* X coord. of cell boundaries. */

x2

 

.

 

.

 

xnx

 

y1

/* Y coord. of cell boundaries. */

y2

 

.

 

.

 

yny

 

DELEV el

/* Default elevation for grid. */

Figure 1. 2D Grid File Format.

 

GRID2D

ID 5758

TYPE 1

DELEV 0.000000000000000e+00

IJ -y +x

DIM 4 4

0.000000000000000e+00

3.333333333333334e+01

6.666666666666667e+01

1.000000000000000e+02

0.000000000000000e+00

3.333333333333334e+01

6.666666666666667e+01

1.000000000000000e+02

Figure 2. Sample 2D Grid File.

 

The card types used in the 2D grid file format are as follows:

Card Type

GRID2D

Description

File type identifier. Must be on first line of file. No fields.

Required

YES

 

Card Type

TYPE

Description

Defines the type of grid as either cell- or mesh-centered.

Required

YES

Format

TYPE i

Sample

TYPE 0

Field

Variable

Value

Description

1

i

0,1

The type code:

i = 0 for mesh-centered

i = 1 for cell-centered

 

Card Type

IJ

Description

Defines the orientation of the i,j indices.

Required

YES

Format

IJ ±idir ±jdir

Sample

IJ +x -y

Field

Variable

Value

Description

1

±idir

±x,±y

The direction corresponding to an increasing i index.

2

±jdir

±x,±y

The direction corresponding to an increasing j index.

 

Card Type

DIM

Description

Defines the dimensions of the grid.

Required

YES

Format

DIM nx ny

x1

x2

.

.

xnx

y1

y2

.

.

yny

Sample

DIM 4 6

0.0

1.0

2.0

4.0

10.0

12.0

14.0

16.0

18.0

20.0

Field

Variable

Value

Description

1

nx

+

The number of cell boundaries in the x direction.

2

ny

+

The number of cell boundaries in the y direction.

3 to (nx+2)

x1-xnx

±

The coordinates of the x boundaries.

(nx+3) to (nx+ny+2)

y1-yny

±

The coordinates of the y boundaries.

 

Card Type

DELEV

Description

Defines a default elevation for the grid.

Required

NO

Format

DELEV el

Sample

DELEV 100.0

Field

Variable

Value

Description

1

el

±

The default elevation.