4.3.31. Tessellate operator

The Tessellate operator is an operator that tessellates high order elements so that they appear curved.

Fig. 4.75 Tessellate operator example

The Tessellate operator supports the following high order element types.

• QUADRATIC_EDGE

• CUBIC_LINE

• LAGRANGE_TRIANGLE

• QUADRATIC_TRIANGLE

• BIQUADRATIC_TRIANGLE

• LAGRANGE_QUADRILATERAL

• BIQUADRATIC_QUAD

• QUADRATIC_QUAD

• LAGRANGE_TETRAHEDRON

• QUATRADIC_TETRA

• LAGRANGE_HEXAHEDRON

• QUADRATIC_HEXAHEDRON

If the Tessellate operator encounters an unsupported element type it will remove the element from the mesh.

4.3.31.1. Changing the tessellation accuracy

The tessalation accuracy is controlled by the Chord error and Field criterion. The Chord error is with respect to the curvature of the element and is ratio of a chord to the distance from the curve and is independent of the scale of the object. The default Chord error is 0.035, which will typically do a good job. The Field criterion is with respect to the error in the field within the element. The default Field criterion is also 0.035, which will also typically do a good job. Reducing the Chord error and Field criterion will both improve the discretization. They should only be decreased if necessary, since reducing them will increase the number of elements a single high order element is tessellated into. This in turn increases the memory usage and the time to perform operations. The number of elements a single high order element gets tessellated into may easily get into the hundreds.

Fig. 4.76 Tessellate attributes window

4.3.31.2. Merging the points

The points from the cells generated by the tessellation can either be shared or not shared by cells. The default Merge points setting will merge the points. Point merging typically only affects the appearance of the Mesh plot. When points are merged, the mesh lines of individual cells of the tessellation will be visible. When points are not merged, the mesh lines of the high order element will typically only be visible.