Additive manufacturing (AM) is growing rapidly in the industry and is dependent on a number of process parameters and complex multiphysics. In the process, metal powder is melted by a laser beam forming a metal structure. Optimization of the process is very hard and is currently dependent on simple melt pool models. Therefore, there is a lot of trial and error involved in finding a robust AM process. To increase the understanding of the process we propose a physical and CFD-based melt pool model. The model includes a three phase conjugated heat transfer transfer solver, where the gas and melted solid (fluid) are treated with the volume-of-fluid method. To accurately capture the flow of the fluid a temperature dependent rheology model is employed. The phase transition occurs over a small temperature span, in which affected cells are transferred to the other phase solver. Finally, a ray trace based heat source model is used to simulate how an array of powder particles on a substrate are partially melted by a laser beam and the final solidified structure is formed.