Splitting by Angle

This function enables surface or volume mesh boundaries to be split according to the included angle between faces.

The operation of splitting by angle is illustrated schematically below.

This would be useful, for example, if four walls of a box had been created as a single boundary, but you would prefer to treat them separately to support different conditions. The separation will only occur if there is a contiguous surface that can be demarcated by the specified angle criterion.

This function will also automatically execute the splitting non-contiguous boundary action, which occurs even if no splitting occurs based on the angle criterion.

To split boundaries by angle, open the Regions node and open the region of interest. Then right-click on the boundary of interest from the Boundaries node. Select Split By Angle... from the pop-up menu.

This opens the Split Boundaries by Angle dialog:

The boundaries that had been selected in the simulation tree are selected, and the Angle defaults to 89 degrees. When the angle between the faces is acute (less than ninety degrees) then an Angle value of less than the internal angle should be specified in order to split the boundary. When the angle between the faces is obtuse (more than ninety degrees) then the specified Angle value should be less than the included angle between the boundary normals. For example, to split a boundary which has faces at 135 degrees to one another, the included angle is 45 degrees, so a value of 44 degrees or less needs to be used to split the boundary. This is illustrated below:

If more than one representation exists then the surface or volume to be operated upon should be selected using the Representation menu. Once a representation is chosen, the Preview button can be used to determine how many boundaries would be created based on the supplied angle. For example:

Here, the default value of 89 degrees would result in the Wall boundary in Region 1 being split into 2 boundaries (the revised original plus a new one). This is a useful tool for determining the effect of the angle value in cases where there is a large variance in angles between boundaries.

Pressing the Apply button will start the boundary splitting process. Should other representations exist for the simulation then they will have to be deleted first since the boundary correspondance between them will no longer be applicable. In this case, the Ok to Delete Representations dialog will appear:

On pressing the OK button, Simcenter STAR-CCM+ will proceed to split the boundaries for the selected representation. A progress bar will be displayed at the bottom of the simulation tree. Once the process is complete messages in the Output window will indicate the new boundaries that were created:

The new boundaries will also appear on the simulation tree. The name(s) of the new boundaries are taken from the source boundary, with an identifying digit appended:

If the boundary could not be split based on the angle that you supplied, then a message to that effect will be displayed in the Output window indicating as such.