CFD APPLIED TO TURBULENT FLOWS IN CONCENTRIC AND ECCENTRIC ANNULI WITH INNER SHAFT ROTATION J. L. Vieira Neto, 1 A. L. Martins, 2 A. Silveira Neto, 3 C. H. Ata´ ıde 1 and M. A. S. Barrozo 1 * 1. Federal University of Uberlˆ andia, School of Chemical Engineering, Building 1K, Campus Santa Mˆ onica, POB 593, 38400-902 Uberlˆ andia, MG, Brazil 2. PETROBRAS R&D Center, Well Technology Sector, 21949-900 Rio de Janeiro, RJ, Brazil 3. Federal University of Uberlˆ andia, School of Mechanical Engineering, Building 1M, Campus Santa Mˆ onica, 38400-902 Uberlˆ andia, MG, Brazil Turbulent flows in concentric and eccentric annuli with and without rotating inner cylinder were investigated by numerical simulations. Similar flows occur in drilling operations of oil wells. Several turbulence models with Reynolds Average Navier–Stokes approach were used in the simulations and the respective models predictions were compared with experimental data from the literature. The simulated results of axial and tangential velocities show a good agreement with the experimental data. As compared with another turbulence models, the simulations with the standard Reynolds Stress model presented a slightly better prediction for most of the responses studied. On a analys´ e des turbulences en espaces annulaires concentriques et excentriques avec ou sans cylindre interne tournant ` a l’aide de simulations num´ eriques. Des ´ ecoulements semblables se produisent lors d’activit´ es de forage de puits de p´ etrole. Plusieurs mod` eles de turbulence avec l’approche de Navier–Stokes en moyenne de Reynolds ont ´ et´ e utilis´ es dans les simulations et les pr´ edictions respectives des mod` eles ont ´ et´ e compar´ ees aux donn´ ees exp´ erimentales de la litt´ erature. Les r´ esultats simul´ es des v´ elocit´ es axiales et tangentielles cadrent bien avec les donn´ ees exp´ erimentales. Comparativement ` a d’autres mod` eles de turbulence, les simulations avec le mod ` ele de tension de Reynolds standard ont pr ´ esent´ e une pr´ ediction l´ eg` erement sup´ erieure pour la plupart des r´ eponses ´ etudi´ ees. Keywords: computational fluid dynamics, turbulence, rotating annular flows INTRODUCTION T he main interest of annular flows study is concerned with the petroleum industry, especially for application of the per- forations mud used in drilling of oil wells. Drilling fluids are usually either water- or oil-based colloidal suspensions. Additives are usually mixed with the fluid to modify its drilling properties, such as barite to increase the mud density, lignosulphonates to reduce flocculation, polymers to modify filtration rates or to act as viscosifiers, each of which may have a significant effect on the fluid rheology (Escudier et al., 1995). In drilling operations, the annular flow cannot be driven with very slow velocities (in laminar regime) to avoid the gravel sed- imentation to the bottom of the well, while extremely turbulent flows can harm the stability of the well. Therefore, it is very impor- tant to get a better understanding of the rotating flow regimes in annular sections. Experimental investigations of the flow velocity characteristics of rotating and non-rotating Newtonian flows in concentric and eccentric annuli have been discussed by Nouri et al. (1993); and Nouri and Whitelaw (1994, 1997). The Laser Doppler Velocimeter (LDV) technique was used in these works to obtain the axial, radial, and tangential mean velocity profiles and their respective fluctuations and crossed correlations. The experimental study of Kaye and Elgar (1958) also com- bined axial and rotational flow in an annulus section with a rotating inner wall. These authors identified the following basic flow regimes in the annular gap: laminar flow, laminar flow with vortices, turbulent flow, and turbulent flow with vortices. Another experimental work of Yamada (1962) showed that the ∗ Author to whom correspondence may be addressed. E-mail address: masbarrozo@ufu.br Can. J. Chem. Eng. 89:636–646, 2011 © 2011 Canadian Society for Chemical Engineering DOI 10.1002/cjce.20522 Published online 30 March 2011 in Wiley Online Library (wileyonlinelibrary.com). | 636 | THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING | | VOLUME 89, AUGUST 2011 |