The stability of the co-current stratified flow of oil and water was investigated experimentally in a horizontal rectangular conduit. Laminar-turbulent transitions were determined for both phases. With the two-phase system the transition to turbulence in the water phase occurred at a higher Reynolds number in the presence of a laminar oil layer provided the input water-to-oil ratio was relatively high, while the transition in the oil phase took place at a lower Reynolds number in the presence of a turbulent water layer. The appearance of first interfacial waves coincided with the transition to turbulence of the less viscous or water phase. This suggests that in the system investigated the resonance mechanism as proposed by Phillips (1957) was responsible for the generation of these first waves. However, at relatively high water flow rates and water-to-oil ratios more pronounced waves were observed which appeared to be generated by an instability in the mean flow.

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Magnesium nucleation was studied over the range of approximately 700 to 950 K in a gas evaporation apparatus. Measured supersaturation ratios ranged from approximately 37 to 4.2 over this temperature range, respectively. A comparison of these data and Classical Nucleation Theory shows that the two are not consistent. Although there is a good correlation between the supersaturation and the temperature data when plotted in accordance with Scaled Nucleation Theory, some of the derived parameters are slightly below the limits predicted by the theory.

Theoretical expressions have been derived for velocity distribution and volumetric flow rates for the co‐current laminar stratified flow of two immiscible liquids in rectangular conduits. Results are presented in terms of the relative depth of the more viscous phase and the pressure gradient reduction factor for a wide range of viscosity and aspect ratios. Theoretical results are reasonably well verified by experimental data at viscosity and aspect ratios of 5.326 and 7.95:1 respectively. The results suggest that a Lockhart‐Martinelli type correlation should be valid at high viscosity ratios and at low input volume fractions of the more viscous phase.

A method for measuring the interfacial structure between a co-current air-water flow using the absorption of light is described. Measurements of the root-meansquared displacement and the frequency spectrum are presented. The use of a Gaussian model to describe the interface is explored.