Symmetry

This node provides a boundary condition for symmetry boundaries. It should only be used when the geometry and expected solution have mirror symmetry. By using symmetries in a model its size can be reduced by one-half or more, making this an efficient tool for solving large problems.

The boundary condition prescribes no penetration and vanishing shear stresses. The boundary condition is a combination of a Dirichlet condition and a Neumann condition:

for the compressible and incompressible formulations. The Dirichlet condition takes precedence over the Neumann condition, and the above equations are equivalent to the following equation for both the compressible and incompressible formulations:

Boundary Selection

For 2D axial symmetry, a boundary condition does not need to be defined for the symmetry axis at r = 0. The software automatically provides a condition that prescribes ur = 0 and vanishing stresses in the z direction and adds an node that implements these conditions on the axial symmetry boundaries only.

Constraint Settings

This section is displayed by clicking the button (

) and selecting .