In the petrochemical industry, multiphase flow, including oil–water two-phase stratified laminar flow, is more common and can be easily obtained through mathematical analysis. However, there is no mathematical, analytical model for the simulation of oil–water flow under turbulent flow. This paper introduces a two-dimensional (2D) numerical simulation method to investigate the pressure gradient, flow field, and oil–water interface height of a pipeline cross-section of horizontal tube in an oil–water stratified smooth flow, which has field information of a pipeline cross-section compared with a one-dimensional (1D) simulation and avoids the significant calculation required to conduct a three-dimensional (3D) simulation. Three Reynolds average N–S equation models (k−ε, k−ω, SST k−ω) are used to simulate oil–water stratified smooth flow according to the finite volume method. The pressure gradient and oil–water interface height can be computed according to the given volume flow rate using the iteration method. The predicted data of oil–water interface height and velocity profile by the model fit well with some available experiment data, except that there is a large error in pressure gradient. The SST k−ω turbulence model has higher accuracy and is more suitable for simulating oil–water two-phase stratified flow in a horizontal pipe.

In this paper, we propose a new hydrodynamic model for gas–liquid two-phase flows in undulant pipelines based on the gas tracking method. The motion of three main forms of gas phase, including elongated bubbles, small bubbles, and gas pockets, is modeled by respective momentum equations. The mass transfer behaviors among the three gas forms, including interior mass transfer of single gas form, are considered. Therefore, the flow patterns along the pipeline can be predicted based on the gas tracking method. Afterward, the integrated pressure gradient of the gas–liquid two-phase flow in undulant pipelines can be obtained with the updated flow patterns. The model validation using the field data of a real pipeline in China shows that the accuracy of this model is within acceptable range. According to the simulation results, how the pipe terrain affects the gas transport and flow patterns is revealed, and sensitive analysis is carried out. These findings are of great practical value to obtain a deeper understanding of gas–liquid two-phase flows in undulant pipelines.

In this paper, experimental investigation on two oil-soluble drag-reducing agents (DRAs) were carried out in stirred vessel by standard six-blade Rushton, based on the application of particle image velocimeter (PIV). Two DRAs (1# and 2#) with different concentrations from 3 ppm to 50 ppm were added into diesel, respectively, and speed of impeller speed was set 400 rpm. Flow field characteristics including turbulence intensity, turbulent kinetic energy (TKE), and energy dissipation rate (EDR) influenced by those additives in stirred vessel were studied. It was found that inhibition effect of turbulence intensity of the two DRAs is not obvious with concentration below 10 ppm. However, when concentration is above 10 ppm, turbulence inhibition effect becomes more obvious. Under low concentration, 1# has better turbulence inhibition effect in the area near impeller, while 2# has better turbulence inhibition effect under high concentration. When the two DRAs are under the same concentration of 50 ppm, turbulent flow energy and energy dissipation rate are obviously reduced.

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The effect of polymer concentration on turbulence flow field was analyzed by particle image velocimetry inside a stirred tank. With the increment of polymer concentration, the velocity gradient in the radial direction increased and the TKE and EDR rapidly decreased in the impeller region, while the velocity gradient decreased in the axial direction and the TKE and EDR first increased and then decreased in the region close to the wall. Higher polymer concentration resulted in lower turbulence intensity both in the radial and axial velocity components attributing to the weakened and restrained fluctuation intensity of the long-chain in the drag reducer polymer.