Documentation for ANSYS ICEM CFD/AI*Environment 11.0 SP1

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O-grid Block

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The O-grid creation capability is simply the modification of a single block or blocks to a 5 sub-block topology (7 sub-blocks in 3D) as shown below. It arranges grid lines into an “O” shape to reduce skew where a block corner lies on a continuous curve or surface. There are several variations of the basic O-grid generation technique.

Figure 22  O-grid Demonstration

O-grid Demonstration

As shown below, the O-grid can be created with or without face selection.

Figure 23  O-grid Creation With and Without Face Selection

a) Circular Cylinder

O-grid Creation With and Without Face Selection

b) Block Inside Cylinder

O-grid Creation With and Without Face Selection

c) O-grid created without face selection

O-grid Creation With and Without Face Selection

d) O-grid created with face selection

O-grid Creation With and Without Face Selection

O-grids can be created or removed by selecting or deselecting Blocks, Faces, Edges, and Vertices. The following options are also available.

Around block(s)

If toggled ON, the O-grid will be created outside the block(s).

Offset

Specify the height of the O-grid layer.

Absolute

If toggled ON, the value assigned for Offset is the actual length of the radial edge of an O-grid. Assigning a Offset of 7 would make all the radial edges of the O-grid 7 units in length.

When Absolute is toggled OFF, Offset behaves like a relative distance: A value of 1 causes the Hexa Mesher to place the O-grid at a location where the resulting blocks will be distorted the least. A higher value makes the inner blocks of the O-grid smaller, with the surrounding blocks larger, and a smaller value makes the inner blocks larger and the surrounding blocks smaller.

Published: 2007-08-13