The symmetry boundary condition defines a mirror face/surface. The symmetry condition should only be used if the physical object or geometry and the expected flow field pattern of the developed solution is mirrored along that surface. Using this boundary condition would halve the time SimScale takes to reach a solution.
In detail, the symmetry condition applies the following constraints on the flow variables:
The symmetry boundary condition can be applied to both planar or non-planar faces/surfaces on the domain boundaries.
This condition should not be used for axisymmetric or periodic flow cases (please refer to the ‘Wedge’ or ‘Periodic boundary condition’ for details on how to approach these).