Infinite Box - 3D Solutions

Introduction

The Infinite Box allows you to create an infinite box.

The infinite box allows to model an infinite domain.



There is only one infinite box per study domain.

Geometrically, it represents two bounding boxes (parallepiped boxes or cylindrical boxes).

The physical boundary conditions are set automatically on the infinite box. The use of the infinite box implicitly assumes a null field at infinity.

Dialog Box

Infinite box "Block" Infinite box "Cylinder"




The Create infinite box dialog box contains the inputs of its geometrical dimensions and mesh.

Note: All those information are automatically computed from device dimensions to be consistent with Flux standard infinite box constraints. Therefore, user can directly click on "OK" without modifying anything. But, if necessary, it remains possible to modify the inputs.
The infinite box can be Block or Cylinder. The Block infinite box can be used for all devices except cases with periodicity. The Cylinder infinite box is only available for cases with periodicity which concerns mainly motors.
  • Here is the content of Block infinite box dialog box:
    • Infinite Box name: the name of the infinite box entity which will be created in the loads and constraints and the prefix of the generated bodies names
    • Center: the coordinates of the infinite box center. It is in read only because it is necessarily centered at device center.
    • Length: infinite box inner air box length in X, Y, Z directions. It is computed automatically from device size: 3 times the device dimension on X, Y and Z direction which is usually a good ratio.
    • Internal air box mesh parameters: It is possible to define internal air box mesh by one of the two following parameters:
      • Number of elements: defines the number of elements on each X, Y, Z directions of the internal air box. It is computed automatically to have 10 elements on the smallest direction, and proportional values on the two other directions. That's allows to have a homogeneous mesh on all the directions.
      • Mesh size: defines the mesh size of the internal air box. It is automatically computed from the previous number of elements computation.
    • Number of elements in external air box layer: defines the number of elements between the internal air box and external air box. It is by default 3 which is usually the advised value if the post processing won't be done inside the infinite box outer layer.
  • Here is the content of Cylinder infinite box dialog box:
    • Infinite Box name: the name of the infinite box entity which will be created in the loads and constraints and the prefix of the generated bodies names
    • Modify Cylinder axis: allows to modify the cylinder infinite box axis. For the moment, cylinder infinite box is available only with periodicity. In this case the axis will be necessarily the periodicity axis. Therefore this button will be always disabled for this version.
    • Height: defines the cylinder height on its axis. By default, it is 3 times the device dimension in this direction which is usually a good ratio.
    • Radius: defines the cylinder radius. By default, it is 1.5 times the radius of the cylinder circumscribing the device. This value is usually suitable for motor cases where there are often less leakage flux. If needed, user can modify this value.
    • Internal air box mesh parameters: It is possible to define internal air box mesh by one of the two following parameters:
      • Number of elements: defines the number of elements on each circular and axial directions of the internal air box. It is computed automatically to have a good compromise between precision and time performance.
      • Mesh size: defines the mesh size of the internal air box. It is automatically computed from the previous number of elements computation.
    • Number of elements in external air box layer: defines the number of elements between the internal air box and external air box. It is by default 2 which is usually the advised value for motor cases (not very high flux leakage).
Note: The Outer air box dimensions and mesh are defined automatically from the inner box mesh and the Number of elements in external air box layer.
The validation of the infinite box creation will create:
  • One Loads and Constraints entity with the chosen infinite box entity name
  • Two volume meshed bodies named with infinite box name with suffix "Outer" and "Inner". Those bodies are assigned to the infinite box loads and constraints entity.
    Block infinite box Cylinder infinite box

Symmetry and periodicity management

When symmetries and periodicity exist, the infinite box is built by taking it into account (see Symmetry and infinite box and Periodicity and infinite box).

Depending on the configuration it is possible to use Block or Cylinder infinite box as described in the following table:

Complete device Symmetric device (no periodicity) Periodic device (without/with 1 symmetry)
Block





Cylinder





Note: In case of periodic device, the generated infinite box will have a periodic mesh on its faces on the periodicity planes. Concerning the device mesh, prior to the infinite box creation user has to define himself the Symmetry Mesh mesh control to obtain a periodic mesh on the periodicity planes faces.

Steps for complete or symmetric device (Block infinite box)

In case of complete device or symmetric device, the Block infinite box is used.

The steps to follow are:
  1. Prerequisite:
    • The device is complete (i.e. the solution doesn't contain any symmetry or periodicity) or symmetric (i.e. the solution contains 1, 2 or 3 symmetries). No periodicity entity exists.
    • The device bodies are volume meshed with the same mesh order.
  2. Click on the Infinite Box button in Analysis ribbon:

    → The corresponding dialog box appears with all inputs filled automatically (computed from device dimensions)

    Note: It is possible to change the input values
    → A preview of the inner infinite box is displayed with its center coordinates and length values:

    Note: The Outer air box dimensions and mesh are defined automatically from the inner box mesh and the Number of elements in external air box layer.
  3. Click on OK to validate the infinite box creation

    → The infinite box entity is created and appears in the Model Browser of Solution tab in the node Loads and Constraints

    → When editing the infinite box entity, the inputs values and the two infinite box layer bodies assigned to the entity are shown (In read only)

    → Those two bodies are visible in the Model Browser of Assembly tab:

    Note: There is no need to assign Air material to the two infinite box bodies.

Steps for periodic device (Cylinder infinite box)

In case of periodic device, the Cylinder infinite box is used.

The steps to follow are:
  1. Prerequisite:
    • The device is periodic (i.e. the solution contains 1 periodicity and optionally 1 symmetry).
    • The device mesh is periodic on the periodicity planes faces (Otherwise, please use the Symmetry Mesh mesh control).
    • The device bodies are volume meshed with the same mesh order.
  2. Click on the Infinite Box button in Analysis ribbon:

    → The corresponding dialog box appears with all inputs filled automatically (computed from device dimensions)

    Note: It is possible to change the input values
    → A preview of the inner infinite box is displayed with its Height and Radius values:

    Note: The Outer air box dimensions and mesh are defined automatically from the inner box mesh and the Number of elements in external air box layer.
  3. Click on OK to validate the infinite box creation

    Please check Steps for complete or symmetric device (Block infinite box) - Step 3 - to see infinite box creation output.

Edit Infinite box

The created infinite box cannot be modified (except the entity/bodies names).

To modify the infinite box, the created infinite box has to be deleted to create a new one. To delete it: Right-click on the infinite box entity and choose Delete.

Limitations

Here are below some limitations on the infinite box:
  • The cylinder infinite box is available only if a periodicity entity exists (not available for a complete device or a device with symmetries).
  • The infinite box cannot be modified. It must be deleted to create a new one.