Example 2 - Using multiple Enclosure Radiation type objects

You can use the Enclosure Radiation type to speed up radiation calculations and to specify special treatment for some parts of the model.

For this model of a pot in an oven, the radiation calculation must be performed for both the interior and exterior of both the oven and the pot.

The arrows show the element normal direction. Some meshed faces require that you also define Thermo-Optical Properties for their bottom side. In the previous figure, such a face is shown with the following arrow: .

This example has the following enclosures: the inside of the pot, the inside of the oven, and the outside of the oven.

• For the enclosure of the inside of the pot, all top sides of the pot elements point inward.

• For the enclosure of the oven interior, the oven elements have their top side pointing inward. Thermo-Optical Properties only need to be defined on the top side of this material, since no radiation passes through the walls of the oven. The pot elements, on the other hand, participate in that enclosure but only from their bottom side, so they need bottom side Thermo-Optical Properties. The reflector also needs that you define bottom side properties since both sides of this surface radiate inside the oven.

• For the enclosure of the outside of the oven, the oven's external surfaces have their element normals pointing outward. Again, to prevent radiation through the wall of the oven, the bottom side Thermo-Optical Properties of this material must not be defined. Because the interior and exterior walls of the oven can have different emissivity, you should assign different Thermo-Optical Properties for each wall.For the outside of the oven to radiate to something, you must:Select Include Radiative Environment in the Radiation dialog box.Define a Radiative Environment Temperature on the Ambient Conditions page in the Solution dialog box.Because the external elements all have an unobstructed view to the environment, no shadowing occurs in this enclosure.

With the active sides of the elements oriented as described, no radiation is calculated between the oven's interior elements and its exterior ones. This is consistent with the fact that heat exchange between these two enclosures occurs through conduction, which you can model with a Thermal Coupling.

Defining this thermal model with three separate Enclosure Radiation type Radiation objects, one for each enclosure, allows the thermal solver to avoid shadowing checks when they are not needed. For the interior oven enclosure, a more precise error criterion can be specified without adding unnecessary calculation elsewhere in the model. The external enclosure is the only one that requires Include Radiative Environment .

Defining this thermal model with a single All Radiation type Radiation simulation object yields the same final temperature distribution, but the solver has to perform additional calculations to determine if any enclosures exist and whether shadowing occurs.

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Example 2 - Using multiple Enclosure Radiation type objects, Simcenter 3D 2021.1 Series

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