AbstractThe objective of the study is to investigate bubble motion and local variables for two-phase flow in reducer pipelines. A three-dimensional computational fluid dynamics (CFD) model using volume of fluid (VOF) method is presented for predicting the development of phase distribution, velocity profiles as well as local and average friction factor using a commercial CFD package FLUENT. Model predictions agree with data reported in the literature. The results reveal that the air and water interface tends to become concave and wavy while fluid travels through the junction of the reducer. The length to achieve fully developed flow increases with increasing pipe contraction. The velocity profiles appear to be prominent in the center of the pipe ahead of the junction. Axial velocity profiles in the horizontal centerline remain symmetrical, but velocity profiles in vertical centerline have velocity peaks near the top of the pipe, where the gas phase exists. Reduction of pipe diameter causes unbalanced incre...
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