6.5.2 Hooking DEFINE_DYNAMIC_ZONE_PROPERTY UDFs

The DEFINE_DYNAMIC_ZONE_PROPERTY UDF can be hooked in order to define the following:

• the swirl center for in-cylinder applications

• a variable cell layering height

Hooking a Swirl Center UDF

After you have complied your DEFINE_DYNAMIC_ZONE_PROPERTY UDF (as described in Chapter  5), the name of the function you supplied as a DEFINE macro argument will become visible and selectable in the In-Cylinder Output Controls dialog box (Figure  6.5.2).

To hook the UDF to ANSYS FLUENT, you will first need to select Transient from the Time list in the Solver group box of the General task page.

General Transient

Next, enable the Dynamic Mesh option in the Dynamic Mesh task page.

Dynamic Mesh Dynamic Mesh

Then, enable the In-Cylinder option in the Options group box, and click the Settings button to open the In-Cylinder Settings dialog box. After you have updated the parameters in this dialog box, click the Output Controls... button to open the In-Cylinder Output Controls dialog box (Figure  6.5.2).

Figure 6.5.2: In-Cylinder Output Controls Dialog Box

Select the UDF library (e.g., swirl_udf::libudf) from the Swirl Center Method drop-down list in the In-Cylinder Output Controls dialog box. Click OK and close the In-Cylinder Output Controls dialog box.

See Section  2.6.2 for further details about DEFINE_DYNAMIC_ZONE_PROPERTY functions.

Hooking a Variable Cell Layering Height UDF

After you have compiled your DEFINE_DYNAMIC_ZONE_PROPERTY UDF (as described in Chapter  5), the name of the function you supplied as a DEFINE macro argument will become visible and selectable in the Dynamic Mesh Zones dialog box (Figure  6.5.3).

Since the DEFINE_DYNAMIC_ZONE_PROPERTY UDF is a function of time or crank angle, you must make sure that you have selected Transient from the Time list in the Solver group box of the General task page before proceeding.

To hook the UDF to ANSYS FLUENT, you will first need to enable the Dynamic Mesh option in the Dynamic Mesh task page.

Dynamic Mesh Dynamic Mesh

Then, enable the Layering option in the Mesh Methods list, and click the Settings... button to open the Mesh Methods Settings dialog box. In the Layering tab, select Height Based from the Options list, and set the Split Factor and Collapse Factor to appropriate values. Then click OK.

Next, specify the meshing options in the Dynamic Mesh Zones dialog box (Figure  6.5.3).

Dynamic Mesh Create/Edit...

Figure 6.5.3: The Dynamic Mesh Zones Dialog Box

Select Stationary, Rigid Body, or User-Defined from the Type list in the Dynamic Mesh Zones dialog box. Click the Meshing Options tab, and select the UDF library (e.g., nonconst_height::libudf) from the Cell Height drop-down list. Finally, click Create and close the Dynamic Mesh Zones dialog box.

See Section  2.6.2 for further details about DEFINE_DYNAMIC_ZONE_PROPERTY functions.