The Symmetry node adds boundary conditions that describe symmetry boundaries in fluid-flow simulations. The boundary condition for symmetry boundaries prescribes no penetration and vanishing shear stresses:

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 Axial Symmetry node that is valid on the axial symmetry boundaries only.