28.6.1 Using the Plane Tool

The plane tool allows you to interactively fine-tune the definition of a plane using graphics. Starting from an initial plane, you can translate, rotate, and resize the plane until its position, orientation, and size are as desired. For example, if you need to position a plane surface at a cross-section of an irregularly-shaped, curved duct, you can start with the plane tool near the desired location, resize it, translate it until it is within the duct walls, and rotate it to the proper orientation. (You may find it helpful to display mesh faces to ensure that the plane tool is correctly positioned inside the domain.)

Initializing the Plane Tool

Before turning on the Plane Tool option, set the Points to suitable starting values. You can enter values manually, or use the Select Points button. Often it is convenient to display the mesh for an inlet or isosurface that is similar to the desired plane surface, and then select three points on that mesh to position the initial plane. Once you have specified the appropriate Points, activate the tool by turning on the Plane Tool option. The plane tool will appear in the graphics window, as shown in Figure  28.6.2.

Figure 28.6.2: The Plane Tool

You can then translate, rotate, and/or resize the plane tool as described below.

Translating the Plane Tool

To translate the plane tool in the direction normal to the plane, click the mouse-probe button (the right button by default--see Section  29.3 for information about changing the mouse functions) anywhere on the gray part of the plane tool and drag the mouse until the tool reaches the desired location. Green arrows will show the direction of motion.

To translate the tool in the transverse directions (i.e., along either of the axes that lie within the plane), press the <Shift> key, click the mouse-probe button anywhere on the gray part of the plane tool, and drag the mouse until the tool reaches the desired location. Two sets of green arrows will show the possible directions of motion. If you find the perspective distracting when performing this type of translation, you can turn it off in the Camera Parameters dialog box (opened from the Views dialog box), as described in Section  29.5.2.

Rotating the Plane Tool

To rotate the plane tool, you will click the mouse-probe button on one of the white arrows at the tips of the plane's axes. Clicking on any arrow allows you to rotate the tool about either of the other two axes: when you click on the arrow, two green ribbons will encircle the plane tool, forming circles about each of the two possible axes of rotation. Drag the mouse along the desired circle to rotate the tool. As you do so, the circle along which the tool is rotating will become yellow.

The following notes may help you when you are rotating the plane tool:

• Once you move your mouse along one circle, you cannot change the direction of rotation unless you release the mouse-probe button and try again. Be careful to start moving your mouse very steadily so that you can choose the correct direction.

• Do not click on the red arrow to rotate.

• Do not try to rotate by clicking on an arrow that is pointing away from you. It will be very difficult for you to judge which direction of rotation is correct from this point of view. Since there are two arrows on each axis, there will always be an appropriate arrow available.

• Do not rotate the plane tool more than 90 $^\circ$ or so at once. If you rotate the tool by a large angle, the arrow on which you are clicking will begin to point away from you, and you will have trouble controlling the rotation (as discussed in the item above).

Resizing the Plane Tool

If you plan to generate a bounded plane, you can resize the plane tool to define the plane's boundaries. Click the mouse-probe button in one of the white squares at the plane tool's corners and drag the mouse to stretch or shrink the tool. Green arrows will show the direction of the plane's diagonal.

Be careful not to drag your mouse across any of the axes while resizing the tool. This will flip the tool over and corrupt it. If you accidentally do this, reset the plane tool and start again.

Resetting the Plane Tool

If you "lose'' the plane tool, or want to reset it for any other reason, you can either click on the Reset Points button to return the plane tool to the default position and start from there, or turn the tool off and reinitialize it as described above. In the default position, the plane tool will lie midway along the $x$ length of the domain, spanning the $y$ and $z$ domain extents.