Model flows for CVD: enforced axial flow and temperature dependent viscosity

We present a numerical study concerning the enforced axial flow of a fluid with temperature dependent viscosity over a rotating disk. It is found that temperature dependencies in the liquid viscosity range narrow the mean velocity profiles and expand the mean temperature profile, while gaseous viscosity behaviour has the reverse effect in both of these cases. Under moderate axial flow the radial, azimuthal and temperature profiles are all entrained closer to the disk surface and the effects of variable viscosity are diminished. A linear stability analysis is performed over an extended range of axial flow strengths and temperature dependencies. Increasing the viscosity temperature-dependence parameter results in both Type I and II modes initially stabilising, before reaching a turning point and destabilising again. Enforced axial flow results in a stabilising effect of the Type I mode for all viscosity temperature-dependencies measured. Weakly enforced axial flow initially destabilises the Type II mode, before restabilising with further increased axial flow strength. The application of the investigated effects are discussed in the context of a chemical vapor deposition reactor.