7.2.2 Solid Conditions

A "solid'' zone is a group of cells for which only a heat conduction problem is solved; no flow equations are solved. The material being treated as a solid may actually be a fluid, but it is assumed that no convection is taking place. The only required input for a solid zone is the type of solid material. You must indicate which material the solid zone contains so that the appropriate material properties will be used. Optional inputs allow you to set a volumetric heat generation rate (heat source) or a fixed value of temperature. You can also define motion for the solid zone. If there are rotationally periodic boundaries adjacent to the solid zone, you will need to specify the rotation axis. If you are modeling radiation using the DO model, you can specify whether or not the solid material participates in radiation.

Inputs for Solid Zones

You will set all solid conditions in the Solid dialog box (Figure  7.2.2), which is opened from the Cell Zone Conditions task page (as described in Section  7.1.4).

Figure 7.2.2: The Solid Dialog Box

Defining the Solid Material

To define the material contained in the solid zone, select the appropriate item in the Material Name drop-down list. This list will contain all solid materials that have been defined (or loaded from the materials database) in the Create/Edit Materials dialog box. If you want to check or modify the properties of the selected material, you can click Edit... to open the Edit Material dialog box; this dialog box contains just the properties of the selected material, not the full contents of the standard Create/Edit Materials dialog box.

Defining a Heat Source

If you wish to define a source of heat within the solid zone, you can do so by enabling the Source Terms option. See Section  7.2.5 for details.

Defining a Fixed Temperature

If you wish to fix the value of temperature in the solid zone, rather than computing it during the calculation, you can do so by enabling the Fixed Values option. See Section  7.2.4 for details.

Specifying the Rotation Axis

If there are rotationally periodic boundaries adjacent to the solid zone or if the zone is rotating, you must specify the rotation axis. To define the axis, set the Rotation-Axis Direction and Rotation-Axis Origin. This axis is independent of the axis of rotation used by any adjacent wall zones or any other cell zones. For 3D problems, the axis of rotation is the vector from the Rotation-Axis Origin in the direction of the vector given by your Rotation-Axis Direction inputs. For 2D non-axisymmetric problems, you will specify only the Rotation-Axis Origin; the axis of rotation is the $z$-direction vector passing through the specified point. (The $z$ direction is normal to the plane of your geometry so that rotation occurs in the plane.) For 2D axisymmetric problems, you will not define the axis: the rotation will always be about the $x$ axis, with the origin at (0,0).

Defining Zone Motion

To define zone motion for a rotating or translating reference frame, select Moving Reference Frame from the Motion Type drop-down list and then set the appropriate parameters in the expanded portion of the dialog box.

To define zone motion for a sliding mesh, select Moving Mesh from the Motion Type drop-down list and then set the appropriate parameters in the expanded portion of the dialog box. See this section in the separate Theory Guide for details.

For problems that include linear, translational motion of the fluid zone, specify the Translational Velocity by setting the X, Y, and Z components. For problems that include rotational motion, specify the rotational Speed under Rotational Velocity. The rotation axis is defined as described above.

See Chapter  10 for details about modeling flows in moving reference frames.

Defining Radiation Parameters

If you are using the DO radiation model, you can specify whether or not the solid material participates in radiation using the Participates in Radiation option. See Section  13.3.6 for details.