Numerical simulation of dispersion in the flow of power law fluids in curved tubes

The influence of non-Newtonian fluid behavior on the flow statistics of turbulent bubble-laden downflow in a vertical channel is investigated. A Direct Numerical Simulation (DNS) study is conducted for power-law fluids with power-law indexes of 0.7 (shear-thinning), 1 (Newtonian) and 1.3 (shear-thickening) in the liquid phase at a gas volume fraction of 6%. The flow is driven downward by a constant volumetric flow rate corresponding to a friction Reynolds number of Reτ≈127.3. The Eötvös number is varied between Eo=0.3125 and Eo=3.75 in order to investigate the influence of quasi-spherical as well as wobbling bubbles and thus the interplay of the bubble deformability with the power-law behavior of the liquid bulk. The resulting first- and second-order fluid statistics, i.e., the gas fraction, mean velocity and velocity fluctuation profiles across the channel, show clear trends in reply to varying power-law indexes. In addition, it was observed that the bubble oscillations increase with decreasing power-law index. In the channel core, the bubbles significantly increase the dissipation rate, which, in contrast to its behavior at the wall, shows similar orders of magnitude for all power-law indexes.

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CFD Numerical Simulation for Downhole Thruster Performance Evaluation

Volume 8: Polar and Arctic Sciences and Technology; Petroleum Technology ◽

10.1115/omae2018-78101 ◽

2018 ◽

Author(s):

Bashir Mohamed ◽

Abdelsalam N. Abugharara ◽

M. A. Rahman ◽

Stephen D. Butt

Keyword(s):

Numerical Simulation ◽

Power Law ◽

Mechanical Design ◽

Pressure Effects ◽

Drilling Mud ◽

Ansys Fluent ◽

Pressure Drops ◽

Drilling Performance ◽

Power Law Fluids ◽

Pressure Pulses

This study focuses on numerical simulation and evaluation of a hydraulically powered downhole Thruster. This device is numerically simulated and evaluated using ANSYS Fluent 17.2 to show its generation of pressure pulses that can induce downhole forces that magnify the downhole dynamic weight on bit (DWOB) using drilling mud. Such magnification of the DWOB can produce axial motion of the Thruster. Such axial motions, as proved by many publications can improve the drilling rate of penetration (ROP), release stuck pipes, and reduce frictions in non-vertical wells. The special inner design of the Thruster creates pressure pulses that can provide load impact on the drill bit leading to the increase of WOB that can enhance the drilling performance. The current stage of the study of the Thruster involves a mechanical design of the Thruster by the SolidWorks and an evaluation of the tool function and performance through pressure effect simulation by ANSYS Fluent 17.2. Initially, water is used as the fluid and the main parameters involved in the analysis are pressure and velocity. However, power-law as a non-Newtonian fluid is also used for comparison study in the section of pressure drop analysis. The results are analyzed based on velocity pressure profiles, pressure drops, pressure effects with applications of various back pressures at several planes using water and power-law fluids.

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