Stationary Wall Properties
A stationary wall is a non-moving wall. For stationary walls, the flow velocity is zero at the wall.
Note:
Use the navigation arrows on the image below to view each tab.
| General | |
| Name |
The Name of the wall appears in the Project Manager window and 3D Modeler window. |
| Wall Thickness | Wall Thickness specifies the effective thickness of the wall. |
| Solid Material | Solid Material specifies the material type for the wall using the Select Definition dialog box. |
| General: Thermal Specification | |
| External Condition: Heat Flux | Heat Flux specifies a uniform fixed rate of heat transfer through the wall. |
| External Condition: Temperature | Temperature specifies a uniform fixed temperature on the outer surface of the wall. |
| External Condition: Heat Transfer Coefficient | Heat Transfer Coefficient specifies convective heat transfer at the outer surface of the wall. The heat transfer coefficient can be set automatically using existing empirical Nusselt correlations for forced convection and natural convection flows. These correlations depend on the geometry of the wall, fluid properties, Reynolds number (for forced convection flows), and Rayleigh number (for natural convection flows). To specify the heat transfer coefficient using correlations select Use Correlation and click Edit Correlation to open the Flow Dependent Heat Transfer Correlation dialog box. To specify external surface radiation, select External Surface Radiation and click Edit Parameters to open the External Surface Radiation dialog box. |
| Inner Surface Radiation | Inner Surface Radiation allows you to specify the default radiation characteristics of the inner surface of the wall. |
| Shell Conduction | Shell Conduction enables conjugate heat transfer on the wall. |
| Slip Flow Boundary | Slip Flow Boundary allows you to set the only the normal component of the velocity to zero at the wall. The flow velocity at the wall is always set to zero (that is, a no-slip boundary condition). For models where the no-slip condition is not appropriate (for example, in flows where the static pressure is very low), you can enable a slip flow boundary |
| Inner Surface Radiation | |
| Surface Material | Surface Material specifies the material type for the side of the wall using the Select Definition dialog box. |
| Radiate To | Select All Objects or Reference Temperature. All Objects specifies that the object or surface exchanges radiation with all other objects and surfaces also specified as subject to radiation with heat transfer. Reference Temperature specifies a fixed temperature to which the selected sides of the object radiate heat. Enter a Temperature and View Factor, which is the proportion of radiation that leaves the plate and contacts surrounding objects. The default view factor is 1.0 and the value of the ambient temperature is the Temperature specified in the Icepak Design Settings dialog box. |
Note: If radiation is enabled but Inner Surface Radiation is disabled, then the emissivity default is used in the calculation even if Inner Surface Radiation is disabled.
Note:
- If needed, you can enter a temperature dependent expression for Heat Transfer Coefficient. See Temperature Dependent Thermal Properties for more information.
- If needed, you can define Temperature, Heat Transfer Coefficient, and Heat Flux as a spatial, or volumetric, profile using an expression and a 3D dataset. See Adding 3D Datasets for more information.
If you select Use Correlation for Heat Transfer Coefficient and click Edit Correlation, the Flow Dependent Heat Transfer Correlation dialog box contains the following thermal information.
| Fluid Material | Surface Material specifies the fluid material type for the external flow using the Select Definition dialog box. |
| Convection Type | Select a Convection Type of Forced or Natural to define the heat transfer mode. |
| Forced Convection | |
| Free Stream Velocity | Free Stream Velocity specifies the external flow velocity. |
| Flow Type | Flow Type specifies a Laminar or Turbulent external flow. |
| Flow Direction | Flow Direction specifies the direction of the external flow. |
| HTC Type | HTC Type specifies the type of the heat transfer coefficient used. For forced convection situations, there are empirical correlations to define a local value of the heat transfer coefficient. To specify an average heat transfer coefficient for the entire wall surface, select Average Values. To specify a locally varying heat transfer coefficient, select Local Values. |
| Natural Convection | |
| Ambient Temperature | Ambient Temperature specifies the ambient external temperature for the fluid surrounding the wall. |
| Surface | Surface specifies the orientation of the surface with respect to gravity. The heat transfer coefficients for natural convection flow depend on the orientation of the wall surface relative to the direction of gravity. To specify the orientation of the surface, select one of the following three options: Vertical, Top, and Bottom. |
If you select External Surface Radiation for Heat Transfer Coefficient and click Edit Parameters, the External Surface Radiation dialog box contains the following thermal information.
| External Surface Material | External Surface Material specifies the material type for the external sides of the wall using the Select Definition dialog box. |
| Reference Temperature | Reference Temperature specifies a fixed temperature to which the selected sides of the object radiate heat. |
| View Factor | View Factor is the proportion of radiation that leaves the plate and contacts surrounding objects. |
Assigning a Stationary Wall and Defining Thermal Properties
To assign a stationary wall object type and define its properties:
- Press F to enable face-selection mode.
- Select and right-click a two-dimensional geometry component in the 3D Modeler window or the history tree.
- From the right-click menu, select Assign Thermal>Wall > Stationary.
- On the General tab, enter a Name for the wall.
- Enter the Wall Thickness.
- Select a Solid Material.
- Select a Thermal Specification.
- If you selected Heat Flux, enter a value for Heat Flux.
- If you selected Temperature, enter a value for Temperature.
- If you selected Heat Transfer Coefficient, enter a value for Heat Transfer Coefficient. If needed, select Use Correlation, click Edit Correlation, and specify the correlation settings in the Flow Dependent Heat Transfer Coefficient dialog box. If needed, select External Surface Radiation, click Edit Parameters, and specify the radiation settings in the External Surface Radiation dialog box.
- If needed, select Inner Surface Radiation.
- If needed, select Shell Conduction.
- If needed, select Slip Flow Boundary.
- Do one of the following:
- If you did not select Inner Surface Radiation, click OK.
- If you selected Inner Surface Radiation, click the Inner Surface Radiation tab.
- In the Inner Surface Radiation tab, click Surface Material to open the Select Definition dialog box. On the Materials tab, select the material for the side of the plate and click OK.
- For Radiate To, click All Objects or Reference Temperature.
- If you selected Reference Temperature, enter a Temperature and View Factor.
- Click OK.
Note:
The boundary condition dialog has a Defaults tab, which contains information related to default settings for the boundary condition properties and the following buttons:
- Save Defaults saves the currently defined properties as the default for newly created boundary conditions.
- Revert to Standard Defaults sets the boundary condition properties to the saved default values.
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Click here for scripting information related to this feature. |