HydroGeoSphere/Interactive Block Grids

Interactive block instructions can be used to generate a grid made up of variably-sized blocks. The user can grade the mesh as desired in each of the 3 principal directions. This is particularly useful for regions in which fine meshes are required, for example, near a discrete fracture or well.

Note that these instructions cannot be used in conjunction with the other grid generation instructions like Generate uniform/variable blocks/prisms.

Generate blocks interactive...End
Causes grok to begin reading a group of interactive block instructions until it encounters an End instruction. The group should contain of at least one instruction for each of the principal directions.
 * &bull; &bull; &bull;

The available instructions are:

Grade x
element size multiplication factor and maximum element size.
 * 1) x1, x2, dxstart, xfac, dxmax Start and end x-coordinate, starting element size,

Grid lines (i.e. elements) are generated along the x-axis from x1 to x2 which grade up in size from dxstart to dxmax. Element sizes are increased steadily by a factor of xfac.
 * &bull; &bull; &bull;

Grade y
As above but for the y-axis.
 * &bull; &bull; &bull;

Grade z
As above but for the z-axis.
 * &bull; &bull; &bull;

Example block grid
The instructions used to generate the mesh shown in Figure 5.2 are: