Release from Grid

Use the node to release rays from a user-defined grid of points.

The section is described below. For all other sections, see Release.

Select an option from the list: (the default), , (3D only), or (3D only).

For and enter based on space dimension (qx,0, qy,0, and qz,0 for 3D components) for the ray positions or click the button (

) to select and define a range of specific coordinates.

If is selected, the number of initial coordinates entered for each space dimension must be equal, and the total number of rays released is equal to the length of one of the lists of initial coordinates. If is selected, the total number of rays released is equal to the product of the lengths of each list of initial coordinates.

For example, suppose a 2D component includes a node with the following initial coordinates:

If is selected, a total of 16 rays will be released, including every possible combination of the initial x- and y-coordinates. If is selected, 4 rays will be released with initial positions (0,2), (1,4), (2,6), and (3,8).

For , enter coordinates for the qc (SI unit: m). By default, the distribution is centered at the origin. Then enter the components of the rc (dimensionless). The rays will be released at specified radial distances and angles in the plane containing the point qc and orthogonal to the direction rc.

Select an option from the list: (the default), , or .

For or enter a value or expression for the Rc (SI unit: m). The default is 1 m. Then enter a positive integer for the Nc (dimensionless). The default is 5.

For enter a list of qr (SI unit: m) directly. An arbitrary number of radial coordinates can be entered in the list. The default is 1 m.

The effect of the setting on the resulting ray placement is illustrated in Figure 3-4. For , the distances between the concentric rings of rays are all equal, but the number density of rays is greater at the center of the distribution than at the outer edge. The option corrects this imbalance by defining nonuniform increments in the radial position between the concentric rings.

Enter a positive integer for the Nϕ (dimensionless). The default is 10.

The total number of rays released (before accounting for distributions of ray direction or auxiliary dependent variables at each release point) is

because a single ray is also released at the center of the distribution.

For , enter coordinates for the qc (SI unit: m). By default, the distribution is centered at the origin. Then enter the components of the rc (dimensionless). The rays will be released at specified radial distances and angles in the plane containing the point qc and orthogonal to the direction rc.

Enter a value or expression for the Rc (SI unit: m). The default is 1 m. Then enter a positive integer for the Nc (dimensionless). The default is 5.

Unlike the grid types described in the previous section, each concentric ring of the grid releases a different number of rays, as shown in Figure 3-5. One ray is always released at the center. The first ring of rays surrounding the center has 6 rays arranged in a regular hexagon. Each ring of rays beyond the first has 6 more rays than the ring preceding it, with the grid points arranged in a regular polygon. The radius increments between consecutive rings are uniform.

The total number of grid points generated is

Thus the relationship between the number of radius intervals and the total number of grid points is quadratic.

In the section, you can click the

and

buttons to visualize the ray release positions. Clicking will cause a point to appear in the Graphics window for every release position. Clicking will cause a bounding box to appear, indicating the spatial extents of the released rays. Examples are shown in Figure 3-6 and Figure 3-7.