What Is a Transform?

Transforms are used by displayers to modify the default position, orientation, or size of the part in the displayer. They are represented by nodes in the object tree which have properties and are subject to common menu items.

Transforms can repeat or mirror parts, or just reposition, resize, or reorient them. The transform feature is for viewing only.

In STAR-CCM+, a transform is used in conjunction with a displayer to allow for the repositioning, reflection, or repeat of parts in a scene. There are six types of transforms in STAR-CCM+:

Periodic transform - this is an automatically generated transform from a periodic interface. This transform automatically extracts the rotation angle, axis of rotation, or translation vector from the interface. It is tied to the interface and hence cannot be edited (except for the number of repeats), and will be deleted if the interface is deleted. Applying a periodic transform to a displayer will show the specified number of copies of the parts in the displayer at the specified periodic intervals.

Symmetric transform - this is an automatically generated transform from a symmetry boundary. This transform automatically extracts the plane of symmetry from the boundary. This transform is tied to the boundary and hence cannot be edited, and will be deleted if the boundary type is changed, or the boundary is deleted. Applying a symmetric transform to a displayer will show the mirror image of the parts in the displayer about the symmetry plane.

Graphics periodic transform - this transform behaves the same as a periodic transform, but it is your responsibility to define the rotation angle, rotation axis, or translation vector.

Graphics symmetric transform - this transform behaves the same as a symmetric transform, but is your responsibility to define the plane of symmetry. The plane is of the form ax + by + cz + d = 0, where a, b, and c are the x, y, and z components of the plane normal and d = -ax0 - by0 -cz0 where x0, y0 and z0 are the origin of the plane.

Simple transform - this transform does not copy the original part, but translates, rotates, or scales the part accordingly. Applying a simple transform to a displayer will transform the parts in the displayer accordingly.

Identity transform - this transform is automatically generated, and is the default transform for all displayers. There are no properties associated with this transform, and when applied to a displayer, will show all parts in the displayer at their natural position, size, and orientation.

A transform can be applied to a displayer to view the entire model for a solution in which only a symmetric or periodic repeating portion was solved. For example, when modeling a compressor stage, one often only solves for a single blade row. It becomes useful to view adjacent blade rows, or even the entire repeating solution. Using a periodic transform as the displayer's transform provides a way to view the complete geometry. Similar arguments apply for a problem with mirror symmetry.

A simple transform can be used in a displayer to view parts which would normally occlude each other by separating them.