The following recommendations appear under the Grid tab (Figure 25.21.3):
If you have not already checked your grid, it is best practice that you do so immediately after reading in your mesh, or after any grid modification. To check your grid go to
Checking the grid will help you detect any grid trouble before you get started with your problem setup. You can learn more about the information obtained when checking your grid, by going to Section 6.5.
After setting up your case using the Dynamic Mesh model, it is worth while to preview your mesh prior to running your simulation. You can preview Zone Motion using the GUI command
Display Zone Motion...
To preview the Mesh Motion, go to
Solve Mesh Motion...
It is important that you preview zone motion first and then mesh motion. Zone motion shows the motion of all dynamic zones with the prescribed rigid body motion, using the graphics library. It is a very fast process and does not alter the mesh. Previewing the zone motion will show you if the motion is setup properly (e.g. zones moving in the wrong direction or rotating about the wrong center). It is much more difficult to detect these problems with mesh motion because small time steps are performed and no continuous animation is shown.
Mesh motion should always be done for dynamic mesh cases with prescribed motion. Mesh motion will only show the validity of the mesh during the simulation. Mesh deformation and dynamic zones without rigid body motion will be considered during a mesh motion preview.
Both the Mesh Motion and Zone Motion panels will have a Preview button which will allow you to view the mesh or zone motion prior to running your case. You can obtain more information on mesh motion and zone motion by going to Section 11.7.3.
If either Axisymmetric or Axisymmetric Swirl is specified in the Solver panel and there are mesh nodes that fall below the X-axis, then it is recommended that you translate the grid. Nodes below the axis are forbidden for axisymmetric cases, since the axisymmetric cell volumes are created by rotating the 2D cell volume about the axis; thus nodes below the axis would create negative volumes. To find out if there are any nodes that lie below the x-axis, perform a grid check (Section 6.5). For information on translating the grid, see Section 6.8.11. To access the Grid Translate panel, go to