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• Physics-Informed neural networks (PINNs) are used for single and two-phase flows. • The study investigates the rising bubble problem with and without heat transfer. • The pertinent physics of wake interaction and thermal boundary layer are discussed. • Physics-Informed neural networks are agnostic to geometry and fluid properties. • The maximum error in the position of the centre of mass by PINN is less than 2.8 %. This paper presents data-driven simulations of two-phase fluid processes with heat transfer. A Physics-Informed Neural Network (PINN) was applied to capture the behaviour of phase interfaces in two-phase flows and model the hydrodynamics and heat transfer of flow configurations representative of established numerical test cases. The developed PINN approach was trained on simulation data derived from physically based Computational Fluid Dynamics (CFD) simulations with interface capturing. The present study considers fundamental problems, including tracking the rise of a single gas bubble in a denser fluid and exploring the heat transfer in the wake of a bubble rising close to a heated wall. Tracking of a rising bubble phase interface of fluids with disparate properties was performed, revealing a maximum error of only 5.2% at the interface edge and a maximum error of 2.8% at the position of the centre of mass. Inferred (hidden variable) flows are studied in addition to a purely extrapolative inverse isothermal bubble case. When no velocity data was supplied, velocity field predictions remained accurate. Rise of an inferred isothermal bubble with unseen fluid properties was found to produce a maximum mean-squared error of 0.28 and centre of mass error of 1.25%. For the case of the rising bubble with a hot wall, the maximum error in the temperature domain using specified boundary conditions was 6.8%, while the bubble position analysis reveals a maximum positional error of 3.6%. These results demonstrate that PINN is agnostic to geometry and fluid properties when studying the combined effects of convection and buoyancy on two-phase flows for the first time. This work serves as a starting point for PINN in multiphase cases involving heat transfer over a range of geometries. Eventually, PINN will be used in such cases to provide solutions for forward, inverse, and extrapolative cases. Each of which represent a dramatic saving in computational cost compared to traditional CFD. Contours of volume fraction (α) and temperature (T*) predicted by the CFD (Top) and PINN (Bottom) for the evolution of flow showing how the rising bubble influences the thermal boundary layer on the wall. [Display omitted] [ABSTRACT FROM AUTHOR]

During drilling or oil recovery, it is common that the formation trap gas invades the vertical wellbore/pipeline to cause the gas-liquid two-phase flow, which brings challenges and dangers to wellbore/pipeline pressure control. In this paper, coupling the interfacial mass transfer theory of slip-rising bubbles based on bubble hydraulics to the gas-liquid two-phase flow theory, a new transient non-isothermal gas-liquid two-phase flow model in the vertical wellbore/pipeline was developed. In this model, the effects of flow regime and heat transfer on the mass transfer rate were considered. The proposed model was validated using the measured experiment data and field data. Using this model, the effect of interfacial mass transfer of slip-rising bubbles on the evolution of gas-liquid two-phase flow in a special gas kick scenario was analyzed. The simulation results indicated that the mass transfer rate between oil dispersion and invasion gas was relatively slow, which made the gas not instantaneously dissolved in the oil dispersion or not instantly saturated the oil dispersion. Under the same gas invasion rate, the fraction and mass of free gas calculated by this model were always larger than those obtained by Yin's model, resulting in a faster of the bottomhole pressure reduction rate and pit gain increase rate. Additionally, increasing the gas concentration and flow rate could promote the interphase mass transfer rate, while increasing the temperature would inhibit it. This model could characterize the wellbore/pipeline gas-liquid two-phase flow with interphase mass transfer in more detail and accurately. [ABSTRACT FROM AUTHOR]