11.3.7 Six DOF Solver Settings

To use the six degree of freedom solver for your transient dynamic mesh simulation, select Six DOF under Options in the Dynamic Mesh task page (Figure  11.3.1) and click the Settings... button. The Six DOF Solver Settings dialog box will open (Figure  11.3.32).

Figure 11.3.32: The Six DOF Solver Settings Dialog Box

You can specify the gravitational acceleration in the x, y, and z directions either in this dialog box, or in the Operating Conditions dialog box. Note that you can also keep track of an object's motion history by selecting the check box next to Write Motion History. A single motion history file will be generated for each moving object which can be used to display zone motion for postprocessing your results. Enter the file name in the File Name text entry box and click OK (Figure  11.3.32).

Using the Six DOF Solver

ANSYS FLUENT's Six Degree of Freedom (6DOF) solver computes external forces and moments such as aerodynamic and gravitational forces and moments on an object. These forces are computed by numerical integration of pressure and shear stress over the object's surfaces. Additional load forces can be added (e.g., injector forces, thrust (propulsive) forces, moments produced by a coil spring, etc.). This technique, along with the ANSYS FLUENT solver and the use of dynamic meshes, can be readily applied to many useful applications, such as store separation [ 70, 76].

Setting Rigid Body Motion Attributes for the Six DOF Solver

When the Six DOF Solver is enabled, you need to provide additional information for rigid body dynamic zones. For instance, you must use a user-defined function to define the six degrees of freedom parameters, and you must set the velocity and angular velocity for the center of gravity. For each moving object, exactly one user-defined function has to be defined, no matter how many zones there are for each object. For more information about the Six DOF Solver settings in the Dynamic Mesh Zones dialog box or rigid body motion, see Section  11.3.9.

Note that you can also keep track of an object's motion history using the Motion Attributes tab.

The commands in this tab generate a single motion history file for each moving object which can be used to display zone motion for postprocessing your results. For more information on zone motion, see Section  11.3.10.