| An advanced fixed-grid enthalpy formulation based finite volume numerical method is developed to solve the phase change problems in complicated geometries.; The numerical method is based on a general non-orthogonal grid structure and a colocated arrangement of variables. Second order discretizations and interpolations are used.; The convergence rate is considerably accelerated by switching-off the velocity in the solidified region in an implicit way. This switching-off technique has a strong compatibility with SIMPLE-like methods. For all test cases conducted in this study, the rate of convergence using the new treatment exceeds that of the other enthalpy formulation-based methods and with less numerical stability constraints, when used in convection-diffusion phase change problems.; For better run in vector computers, The Incomplete LU decomposition (ILU) matrix solver is partially vectorized. The Mflops (million floating point operation per second) number is raised from 60 to over 300.; Water freezing in orthogonal and non-orthogonal geometry are studied under the effect of density inversion. All thermo-physical properties of the water are dealt with as temperature-dependent (no Boussinsq approximation). The results show a profound effect of density inversion on the flow/energy field and on the local as well as on the universal freezing rate. |
