THE STABILITY OF A COMPRESSIBLE FLUID WITH VARIABLE TRANSPORT-PROPERTIES IN A HORIZONTAL CHEMICAL-VAPOR-DEPOSITION REACTOR

A linear stability analysis was performed to determine the point of on set of longitudinal rolls in a horizontal duct of rectangular cross-se ction with a heated bottom surface, approximating a typical horizontal chemical vapour deposition reactor. The fluid was considered to be co mpressible with temperature-dependent transport properties. It was fou nd that nitrogen is a less stable carrier gas than helium. The effect of the temperature-dependent transport properties was to render less s table the flow in the duct with a bottom surface temperature of 700 K in comparison with the duct with the bottom surface at 1000 K. This in teresting result emphasizes the importance of taking into account the temperature dependence of fluid properties. Comparison with the Boussi nesq-fluid constant-properties model showed that that model can be con siderably in error, depending on the reference conditions for property evaluation and on the particular carrier gas.