Cats2D is a software application used to solve equations for conservation of mass, momentum, and energy in arbitrary two-dimensional geometries, both planar and axisymmetric (including swirl). The code, based on the powerful Galerkin finite element method, can be used to solve stationary or time-dependent problems with free and moving boundaries, for any number of materials or phases, including phase change.
Download user manual (1.1 Mb PDF)
Cats2D resume with publications (64 Kb PDF)
In addition to the user manual, I have put together a tutorial on the formulation of the moving boundary problem with special attention to the case of solidification of a material of unequal liquid and solid densities. The development and physical interpretation of self-consistent boundary conditions for flow, energy, and mass transport is not altogether obvious for this type of problem.