Creating Blocks, Splitting, and Deleting

Blocks are polygons with a mesh inside. They can be created from closed (water-tight) polygons using the blocking tool (blockingtoolbutton) or auto-blocking tool (autoblocking). Closed simply-connected polygons with 3- or 4-sides can be meshed using either structured or unstructured mesh; all other polygons are meshed with unstructured mesh only. Examples of various blocks with structured, unstructured and mixed meshes are shown in the animated figure below.

../../../../../../../_images/blocked_polygons.gif

Figure 1: Clicking on closed polygons with the blocking tool causes them to be meshed

Create a Single Block

blockingtoolbutton     Using the Blocking Tool

  • Select the blocking tool from the toolbar.
  • Move the cursor inside a closed polygon.
  • When the polygon is highlighted (blue indicates the created block will produce a structured mesh, pink indicates an unstructured mesh), click to create the block.

          Using Coordinates

  • With the blocking tool active, press spacebar and enter coordinates. If the coordinates supplied lie within a closed polygon, A block is created.

Create Multiple Blocks

blockingtoolbutton     Using the Blocking Tool

  • Select the blocking tool from the toolbar.
  • Click-and-drag a rectangle around the blocks to be created.
  • Release the left mouse button to finish creating meshed blocks.

autoblocking     Using the Auto-blocking Tool

  • Press the auto-blocking tool button on the toolbar. All closed polygons in the sketch become blocks with structured or unstructured meshing, depending on the shape of the polygon and the zoning specifications along the polygons’ edges.

Structured Mesh Operations

Splitting

blockingtoolbutton     Using the Blocking Tool

  • Position the tool within an existing structured-mesh block. Cyan crosshairs at the mouse position indicate the prospective split. If the mouse is positioned at an edge, the split operation will split that edge.
  • Click to execute the split. Splitting propagates in both directions across the model through all attached blocks with structured mesh.
../../../../../../../_images/splitting_a_block.png

Figure 2: Clicking with the blocking tool within a previously defined block will split the block as indicated by the cyan crosshairs.

          Using Coordinates

  • With the blocking tool active, press spacebar. The current mouse position’s coordinates are displayed. Provide the desired coordinates for the split and press Enter to complete the split.

Zone Multiplier

The zoning in a structured-mesh block may be increased by using the “Zone Mult.” property. When this property is set, the number of zones specified along the edges of a block will be multiplied by the value provided (which must be an integer).

Unstructured Mesh Operations

Re-Blocking

Any operations that change geometry of any of the elements of a block with unstructured mesh (e.g. moving nodes, changing edge zoning, splitting an edge, etc.) causes removal of the block’s unstructured mesh. In such a case, re-blocking the polygon (using any of the methods described above) is necessary to account for the new geometry.

Delete

selecttool     Using the Select Tool

  • Select a block.
  • Press Ctrl and select additional blocks to add to the selection.
  • Press Delete to delete the selected blocks.

Using the Right Mouse Button

Bear in mind that when the blocking tool (blockingtoolbutton) is active, the regular selection functions of the select tool (selecttool) are available from the blocking tool’s right mouse button, as described in Right-Click Selection Overload.