The default of this solver is 3D. But an option for 2D problem calculations is also provided. If the user wants to use this 2D solver, they must have a mesh that has only a single layer of elements in the z-direction (i.e., a 2D x-y mesh (quadrilateral or triangular mesh) but extended in the z-direction). Also, the user should not define the boundary conditions on the z-direction boundary surfaces (both sides). Then the code will automatically check for this setup, and use the 2D solver if a 2D mesh was detected. This saves a lot of CPU time for some problems.
A 2D axisymmetric flow option is also available with this solver. In order to make use of this option, the above 2D requirements must be satisfied. In addition, the x and y coordinates must correspond to the axial and radial directions respectively. Currently, this option only works on hexahedral meshes (quads in 2D case).