Create a Wall Condition

The “wall” type of Boundary Conditions allows you to create impermeable boundary conditions on selected fluid-contacting faces for both Internal and External analyses.

Prerequisites

The Fluid Flow and/or Conduction option must be enabled on the Analysis Type tab of the General Settings or Wizard dialog.

Procedure

Open the Boundary Condition dialog:
- On the ribbon, click Flow Simulation > Insert > Conditions > Boundary Condition.
- On the toolbars, click Boundary Condition on the Flow Simulation Features toolbar.
- In the menu, select Tools > Flow Simulation > Insert > Boundary Condition.
- In the Flow Simulation Analysis tree, right-click the Boundary Conditions item and select Insert Boundary Condition.
- Right-click a model face in the graphics area and select Insert Boundary Condition to create a boundary condition on the selected face.
Under Selection, select faces on which you intend to specify the boundary condition in the graphics area (see “Selection List” for details).
The selected faces and components appear in the Faces to Apply the Boundary Condition list.

In case of several fluid subdomains, the Fluid Subdomain list is available for selecting the desired fluid region. If the CAD Boolean or Preprocessor Boolean geometry recognition is specified, this list is for information only (see “Specify an Analysis Type and Physical Features” for details).
You can also select a reference coordinate system, if you intend to specify either a fluid swirl or 3D velocity vectors, or non-uniform flow parameter distribution over the selected faces:
- The reference Coordinate System selected by default can be:
  - Face Coordinate System (for single planar faces). The origin of face coordinate system is located at the center of the face and its X axis is oriented normally to the face.
  - Global Coordinate System (for non-planar faces or if more than one planar face is selected). See “Global Coordinate System” for details.
  Tip
  You can replace the default coordinate system by selecting your coordinate system in the flyout FeatureManager design tree.
  
  To create a coordinate system, click Insert > Reference Geometry > Coordinate System.
- If you want to use a cylindrical Coordinate System, select the axis of the specified Coordinate System as the Reference axis. The selected Coordinate System and Reference axis also define a local spherical coordinate system.
Under Type, select the Walls type and then select an appropriate type of boundary conditions:
- By applying the Real Wall condition to the selected fluid-contacting walls you can specify roughness and/or heat transfer coefficient and/or wall temperature values, that are different from the default values specified in the Wizard or General Settings dialog.
  
  The Real Wall condition also allows you to specify tangential velocity boundary condition at a wall to simulate translation or rotational motion of the wall (see “Specify Wall Motion” for details).
  
  In addition (if the Rotation option is enabled on the Analysis Type tab of the General Settings or Wizard dialog), you can select the Stator check box, if you want to specify a stationary wall (in the absolute, non-rotating reference frame) within a local region of rotation or when the global rotating reference frame is enabled. When the Stator type of wall is selected, the tangential velocity at this face is equal to zero.
- The Outer Wall condition allows you to specify the outer wall temperature or heat transfer coefficient together with the external fluid temperature for the selected external walls in an Internal flow analysis and if the Conduction option is enabled on the Analysis Type tab of the General Settings or Wizard dialog.
- The Ideal Wall condition allows you to specify all selected faces as adiabatic, frictionless walls instead of the default fluid friction walls (see also “Default Wall Conditions”).
  
  Tip
  If appropriate, you can choose the Ideal Wall condition to introduce a flow symmetry plane, which can assist in reducing required computational resources.
If Real wall or Outer wall is selected as the boundary condition type, under Wall Parameters you can specify the conditions on the selected walls (see “Specify Wall Parameters” for details).
If you want to specify a coordinate-dependent value, click Dependency to the right of the parameter value input box (see “Dependency” for details).
Under Goals you can select goals to associate with the boundarycondition.Those goals are created together with the condition and remain connected with the same geometry.
It is often convenient to specify an appropriate goal along with the boundary condition. For example, if you specify a pressure opening, it makes sense to define a mass flow rate surface goal for this opening.
When creating a new boundary condition, under Name Template in the Name Template box you can specify a template for its name.
The default template is <Type> and <Number>, where <Type> is the boundary condition type and <Number> is the sequential number of the boundary condition in the Flow Simulation Analysis tree. When boundary condition is created, <Type> is replaced by the boundary condition type (for instance, “Real Wall”) and <Number> is replaced by the sequential number of the boundary condition (for example, if the boundary condition named “Real Wall 1” already exists, the new boundary condition will be named “Real Wall 2” and so on). You can combine these standard elements in any order and add any appropriate characters to the template. To add a new standard element to the template, click the Type or Number button
Click OK .
-or-

Click Keep Visible before clicking OK to keep the dialog open and define more boundary conditions.

Results

The new Boundary Condition item appears in the Flow Simulation Analysis tree.

To edit definition of the Boundary Condition, in the Flow Simulation Analysis tree, double-click the Boundary Condition item, or right-click the item and select Edit Definition.

Also you can use a callout in the graphics area to edit definition of a Boundary Condition or a multiple condition definition to edit multiple materials at once (see “Feature Callout” and “Editing Multiple Items at Once” for details).