A new option has been added to CFD-ACE+ in version 2007.2 that will allow the user to solve turbulence on a zone by zone basis, i.e. some zones can be specified as laminar while others are specified as turbulent.  This is available for use with all turbulence models in CFD-ACE+.

Usage:

First, activate the Flow and Turbulence modules on the PT tab, then select the desired Turbulence model on the MO --> Turb tab.  To deactivate turbulence for certain zones, go to the VC tab and select Turbulence for the VC Setting Mode.  The option to solve for turbulence in a zone is displayed when a volume is selected.  Select all zones where turbulence should not be solved and uncheck the box next to Turbulence (these will be laminar zones), as shown in Figure 1.

Figure 1.  Zone by zone turbulence specification in CFD-ACE-GUI 

If needed, the turbulence quantities may be specified at the interface boundaries between turbulent and laminar zones.  In most cases, this is not required. 

Selected Case:

The following driven cavity flow demonstrates this new feature.  The main pipe at the top is turbulent will the vertical cavity is laminar.  A plot of the turbulent viscosity is shown in Figure 2. In the cavity the values are zero as expected.

Figure 2.  Turbulent viscosity shown for the turbulent regions.

This model could have also been used for the airfoil or flat plate cases.  However the user will have to construct the computational grid so that the interface between zones falls at the transition location.  An example of a double heat exchanger showing the turbulent zone by zone feature is available in the V2007.2 release notes.

There were several new turbulence features in the V2007.2 release.  We hope you will try this or one of the others in your simulation efforts if applicable.  For any questions about this user tip or if you have a topic for a future tip, please contact the customer support staff.

Regards,
Perry Daley
ESI CFD Support Team