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.

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The available instructions are:

Grade x

1. x1, x2, dxstart, xfac, dxmax Start and end x-coordinate, starting element size,

element size multiplication factor and maximum 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.

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Grade y

As above but for the y-axis.

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Grade z

As above but for the z-axis.

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Example block grid

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

generate blocks interactive

grade x
 75.0    0.0   0.01   1.5   5.
grade x
 75.0  100.0   0.01   1.5   5.
grade x
125.0  100.0   0.01   1.5   5.
grade x
125.0  200.0   0.01   1.5   5.
grade y
100.0    0.0   0.01   1.5   5.
grade y
100.0  200.0   0.01   1.5   5.
grade z
  1.0    0.0   0.25   1.0   0.25
grade z
  3.0    1.0   0.01   1.3   0.25
grade z
  3.0   11.0   0.01   1.3   0.25
grade z
 11.0   12.0   0.25   1.0   0.25

end generate blocks interactive

Figure 5.2: Example Grid which was Created Using Generate blocks interactive Instructions