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26.3.1 Performing Boundary Adaption

You can perform the boundary adaption in three different ways based on:

You can use any of these methods in the Boundary Adaption panel (Figure  26.3.3).

Adapt $\rightarrow$ Boundary...

Figure 26.3.3: The Boundary Adaption Panel
figure



Boundary Adaption Based on Number of Cells


The procedure for performing adaption based on the distance of a cell from the boundary in terms of the number of cells is as follows:

1.   In the Boundary Adaption panel (Figure  26.3.3), select Cell Distance under Options, choose the boundary zones near which you want to refine cells in the Boundary Zones list, and click Apply.

  This operation is performed to fill the cell distance variable for each cell to be visualized in Step 2.

2.   (optional) Click the Contours... button to open the Contours panel.

(a)   Enable Filled contours, disable Node Values.

(b)   Choose Adaption... and Boundary Cell Distance in the Contours of drop-down list.

(c)   Select the appropriate surfaces (3D only).

(d)   Click Display to see the location of cells with each value of boundary cell distance.

By displaying different ranges of values (as described in Section  28.1.2), you can determine the cell distance of the cells you wish to adapt.

3.   Set the Number of Cells to the desired value.
  • If you retain the default value of 1, only those cells that have edges (2D) or faces (3D) on the specified boundary zone(s) (i.e., those cells with a boundary cell distance of 1) will be marked or adapted.

  • If you increase the value to 2, cells with a boundary cell distance of 2 will also be marked/adapted, and so on.

4.   (optional) If you want to set any adaption options (described in Section  26.12), click on the Controls... button to open the Grid Adaption Controls panel.

5.   Click Mark to mark the cells for refinement by placing them in an adaption register (which can be manipulated as described in Section  26.11.1), or click Adapt to perform the refinement immediately.



Boundary Adaption Based on Normal Distance


The procedure for performing refinement based on a cell's normal distance from the boundary (i.e., distance of cell centroid from the boundary) is as follows:

1.   In the Boundary Adaption panel, select Normal Distance under Options, choose the boundary zones near which you want to refine cells in the Boundary Zones list, and click Apply.

  This operation is performed to fill the cell distance variable for each cell to be visualized in Step 2.

2.   (optional) Open the Contours panel by clicking on the Contours... button.

(a)   Enable Filled contours, disable Node Values.

(b)   Choose Adaption... and Boundary Normal Distance in the Contours of drop-down list.

(c)   Select the appropriate surfaces (3D only).

(d)   Click Display to see the location of cells with each value of normal distance.

By displaying different ranges of values (as described in Section  28.1.2), you can determine the normal distance of the cells you wish to adapt.

3.   Set the Distance Threshold to the desired value. Cells with a normal distance to the selected boundary zone(s) less than or equal to this value will be marked or adapted.

4.   (optional) If you want to set any adaption options (described in Section  26.12), click on the Controls... button to open the Grid Adaption Controls panel.

5.   Click Mark to mark the cells for refinement by placing them in an adaption register (which can be manipulated as described in Section  26.11.1), or click Adapt to perform the refinement immediately.



Boundary Adaption Based on Target Boundary Volume


This boundary adaption allows you to produce exponentially larger (or smaller) cells as you get further from the boundaries. The cells are marked for refinement based on the following equation:


 V_n > V_{\rm boundary}e^{\alpha d} (26.3-1)

where $V_n$ is the cell volume, $V_{\rm boundary}$ is the specified boundary volume ( Boundary Volume), $\alpha$ is the exponential growth factor ( Growth Factor), and $d$ is the normal distance of the cell centroid from the selected boundaries. $V_{\rm boundary}e^{\alpha d}$ is the target volume for a cell.

The procedure for this type of boundary refinement is as follows:

1.   In the Boundary Adaption panel, select Volume Distance under Options, set the Boundary Volume and Growth Factor to the desired values, choose the boundary zones in the Boundary Zones list where you want the Boundary Volume to be applied, and click Apply.

  This operation is performed to fill the cell distance variable for each cell to be visualized in Step 2.

2.   (optional) Open the Contours panel by clicking on the Contours... button.

(a)   Enable Filled contours, disable Node Values.

(b)   Choose Adaption... and Boundary Normal Distance in the Contours of drop-down list.

(c)   Select the appropriate surfaces (3D only).

(d)   Click Display to see the contours of the target volume.

By displaying different ranges of values (as described in Section  28.1.2), you can determine the normal distance of the cells you wish to adapt.

You can modify the values of the inputs ( Boundary Volume, Growth Factor, and/or Boundary Zones), click Apply in the Boundary Adaption panel, and then redisplay the contour plot to visualize the modified target volume distribution.

3.   (optional) If you want to set any adaption options (described in Section  26.12), click on the Controls... button to open the Grid Adaption Controls panel.

4.   Click Mark to mark the cells for refinement by placing them in an adaption register (which can be manipulated as described in Section  26.11.1), or click Adapt to perform the refinement immediately.


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