Symmetry for Surface-to-Surface Radiation

Use this node to calculate view factors on only a part of a symmetric geometry to improve efficiency, by defining either one symmetry plane in 2D, 2D axisymmetric, and 3D components, multiple perpendicular symmetry planes in 2D and 3D components; or sectors of symmetry in 2D and 3D components. In addition, a reflection plane can be defined inside each sector of symmetry. Table 6-7 summarizes the available options for each dimension.

Table 6-7: Options for symmetry definition, example with 5 sectors.
Symmetry Type	2D	2D axisymmetric	3D
One Plane
Two Planes		Not applicable
Three Planes	Not applicable	Not applicable
Sectors		Not applicable
Sectors and Reflection		Not applicable

Depending on component’s dimension, select the to be defined:

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In 2D components, select between (default), , or .

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In 2D axisymmetric components, only the option is available.

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In 3D components, select between (default), , , or .

Depending on the selected from the list and on the dimension, further settings are required.

When is selected (default), all external radiation sources are duplicated with respect to the symmetry condition. Otherwise, the external radiation sources do not follow the symmetry condition.

Plane of Symmetry

The coordinates of the points defining the plane should be set:

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In 2D components, the symmetry plane is defined by two points. If the is , set the and coordinates of the and of the . Else, if the is , you can directly select the points from the window. In the and sections, first use the button to toggle between turning ON

and OFF

selections, that is, making the selections active for that selection list. Then select the points from the window.

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In 2D axisymmetric components, the symmetry plane is parallel to the z=0 plane. If the is , set the, zsym. Else, if the is , you can directly select the point from the window. In the section, first use the button to toggle between turning ON

and OFF

selections, that is, making the selection active for that selection list. Then select the point from the window.

•

In 3D components, the symmetry plane is defined by three points. If the is , set the , , and coordinates of the , the , and the . Else, if the is , you can directly select the points from the window. In the , , and sections, first use the button to toggle between turning ON

and OFF

selections, that is, making the selections active for that selection list. Then select the points from the window.

The check box is selected by default. Clear it to hide the plane in the window.

Two Perpendicular Planes of Symmetry

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In 2D components, the planes intersection line is along the out-of-plane direction. The and the from Cartesian axis, θ, should be defined.

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In 3D components, the line can be set , , or . A and the from Cartesian axis, θ, should be defined. The position of the point along the intersection line can be arbitrary as it does not change the planes definition. The direction of the angle θ can be checked in the figure displayed below the settings, for each case of alignment of the intersection line.

The check box is selected by default. Clear it to hide the planes in the window.

Three Perpendicular Planes of Symmetry

The planes are parallel to the Cartesian axis. Only the should be defined.

The check box is selected by default. Clear it to hide the planes in the window.

Sectors of Symmetry

The coordinates of the points defining the symmetry axis should be set:

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In 2D components, the symmetry axis is the out-of-plane vector, and the center of the symmetry must be defined. Set the and coordinates of the .

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In 3D components, the symmetry axis is defined by two points. Set the , , and coordinates of the and the .

Enter a value for the . This should be a numerical value greater or equal to 2.

If the check box is selected, set the coordinates of the , u. This option can be used when each sector has itself a plane of symmetry.