Large‐eddy simulation of downhole flow: The effects of flow and rotation rates

Abstract

The present paper concerns large-eddy simulations of turbulent downhole flow for six Reynolds numbers and five Taylor numbers. Swirl parameter within the range (0-0.98), which compares the effects of the rotation and the flow rates, was evaluated. In this work, the fluid is injected through the drill pipe and then accelerated by the nozzle. As the fluid discharges from the nozzle, a high speed jet is generated in the downhole region, the fluid then impinges the bottomhole surface and finally flows out the downhole region through the annulus. The nozzle is represented by a sudden contraction. The dynamic subgrid scale model has been used to calculate the turbulent viscosity. The immersed boundary method is employed to represent the solid walls of the proposed geometry. Coherent structures appear as spiral rolls into the nozzle and their inclination angles depend on the rotational speed. When the rotational speed increases, these structures are more aligned with the tangential direction. Due to the geometry of the problem, a toroidal vortex takes place and it grows as the Reynolds number increases. The magnitude of the velocity fluctuations increase in the jet region and near the sidewall with increasing flow rate; it also increased in the jet region with increasing rotational speeds.The impact force and the peak pressure on the impacted surface increases with increasing flow rates. Good agreement of the impact force with other works supports the present work methodology.

Application of the Euler–Lagrange Approach and Immersed Boundary Method to Investigate the Behavior of Rigid Particles in a Confined Flow

“…The reliability of the numerical platform is supported by previously performed verification processes (with manufactured solutions for the pressure field and other expressions for the velocity components and pressure) and validations (incompressible laminar jet, laminar and turbulent lid-driven cavity flows) [14,15]. Based on the proposed problem to be studied, a specific Re is considered.…”

“…Successful results can be obtained when the IBM is employed to deal with static geometries [13][14][15][16] and imposed motion geometries with considerable displacements and fluid-structure interaction problems [17][18][19]. The greatest advantage of IBM is that the geometry, particles' motion, or deformation do not imply the need for grid restructuring at every single time step.…”

“…which leads to a system of algebraic equations which is performed by the packages Epetra, AztecOO and ML, in the Trilinos framework [14]. Then, the corrector step can be performed, in which the velocity field…”