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This numerical study investigates the dynamics around a single Taylor bubble rising with small-dispersed bubbles in a vertical pipeline. The Volume-of-fluid (VOF) method in Ansys Fluent 18.1 is used to track the Taylor bubble, and the Discrete Particle Method (DPM) is used to track the small-dispersed bubbles, for the following parameter range; $$812 \leqslant \text{Re} \leqslant 5684$$ , $${\kern 1pt} Eo = 94$$ and $$\log (Mo) = - 10.6$$ . The coupling strategies for both the continuous gas–liquid phase as well as the discrete bubble phase are all accounted for in the numerical calculations. The dispersed bubbles significantly affect the behaviour of the rising Taylor bubble in numerous ways. The terminal velocity increases with an increase in the number of dispersed bubbles. The rise velocity is, however directly correlated with the deformation of the nose of the bubble. The flow dynamics around the nose of the Taylor bubble are stronger for low velocities due to lower inertia. The computations also demonstrated that there are both acceleration and deceleration effects on the Taylor bubble. Our predictions are in quantitative agreement with published experimental results by Cerqueira and Paladino (Int. J. Multiph. Flow, vol. 133, p. 103,450, Dec. 2020).

This is an incompressible numerical study of the hydrodynamics and heat transfer characteristics of Taylor flow in vertical oil and gas pipelines under constant heat flux using the Volume-of-fluid (VOF) method in ANSYS Fluent, covering a wide range of Re(0.22 ≤ Re ≤ 800) and Ca(0.0075 ≤ Ca ≤ 0.35). Nusselt number (Nu) correlations were used to examine the heat transfer characteristics based on a set of flow parameters. A comparison of the predictions of the void fraction, average velocity, pressure drop and the mean Nusselt number was made with available experimental observations, with most of the experimental data falling within 15.540% of the current study. The bubble increases in length with increasing capillary number and the wall of the tube at the confines of the gas phase leads to asymmetric and axisymmetric bubbles at low and high capillary numbers respectively. The transition region between the edge of the bubble and the film thickness increases with an equivalent increase in Ca and more evident at high Re. The study revealed that, Taylor flow plays a more significant role on the pressure drop increase and, provided the mechanisms and theoretical guidance for heat transfer characteristics in oil and gas pipelines.