I have used CFX4 for axisymmetric calculations using a 2D mesh. In CFX4 I specified a boundary condition at the rotation axis. How can I set up a similar calculation in CFX5 using a 2D mesh from ICEM or CFX4
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It is not possible to set a rotation axis boundary conditions in CFX5, however it is possible to solve the problem you ask for in one of three different ways. 1) If you have a 2D axisymmetric mesh in CFX4, this can be imported directly into CFX5. Under mesh import in CFX5 choose mesh format CFX-4. Under `Advanced options` turn on Import 2D Axisymmetric Mesh. The defaults options Num of Planes set to 2 and and Angle(deg) set to 2 should be sufficiently accurate. 2) A similar mesh can be setup using ICEM CFD 5.1. Generate your 2D mesh in ICEM. Under `Blocking` press 2D to 3D button. Set method to Rotate. Specify center of rotation and axis of rotation. Specify the angle e.g. 5 degrees. Set Points per copy to 2. Ensure that Collapse Axis Nodes is turned on. Clicking Apply generates the volume mesh which can exported from ICEM and imported directly into CFX5. This mesh is identical to the mesh used in 1) assuming the 2D meshes are identical. 3) Both 1) and 2) will have skew cells near the axis. In most cases the accuracy is sufficient, however a workaround for this problem would be to generate the volume mesh using a Y-grid topology. With this method it is not possible to use the 2D mesh. |
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