# cart (1d, 2d, 3d)¶

Used for defining a grid with regular spacing in the x, y, and z directions.

## Parameters¶

lower (float vector)
Defines the lower x, y, z coordinates in the form lower=[XLOWER, YLOWER, ZLOWER]. In 1D only 1 component is required, in 2D 2 components, in 3D 3 components. Extra components are ignored.
upper (float vector)
Defines the upper x, y, z coordinates in the form upper=[XUPPER, YUPPER, ZUPPER]. In 1D only 1 component is required, in 2D 2 components, in 3D 3 components. Extra components are ignored.
cells (integer vector)
Defines the number of cells in the domain, cells=[CELLSX, CELLSY, CELLSZ]. Extra components are ignored, and in 1D only the first component is used, similarly in 2D only the first 2 components are used and in 3D the first 3 components are used.
isRadial (boolean)
Defines whether or not coordinates are radial (r, $$\theta$$, z) or Cartesian (x, y, z).
periodicDirs (integer vector)
Define the directions where periodic boundary conditions will be applied. perioddicDirs = [0, 1] tells USim that the grid is periodic in the X and Y directions if a periodicCartBc is called.
ghostLayers (integer)
Tell USim how many ghost layers the grid should use. The default value is 1.
writeGeom (boolean)
Tell USim whether or not to write out geometrical data. Defaults to false.
writeConn (boolean)
Tell USim whether or not to write out connectivity data. Defaults to false.
writeHalos (boolean)
Tell USim whether the halo data and grid should be dumped. Defaults to false. Useful for debugging.

## Example¶

Sample code block

<Grid domain>
kind = cart2d
ghostLayers = 2
lower = [0.0, 0.0]
upper = [1.0, 1.0]
cells = [CELLX, CELLSY]
periodicDirs = [0]