2D and axisymmetric capabilities

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).