This work focuses on numerical modeling of temperature field and mass transport in a so-called modified physical vapor transport (M-PVT) growth configuration, which is a further development of the state-of-the-art SiC bulk crystal growth technique. Modeling has been carried out by adapting the commercial computer code CFD-ACE+ (CFD Research Corporation) to the special application. In particular, linked to experimental results in the own lab, we will first show that modeling may be applied to numerically reproduce the impact of an additional gas inlet on the resulting effective mass transport inside the growth setup. In a second step, we will use modeling to understand the physical and chemical processes during crystal growth. We will show how additional gases may be used to tailor the gas phase composition, i.e. C/Si ratio, in front of the SiC growth interface. (c) 2007 Elsevier B.V. All rights reserved.