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http://hdl.handle.net/10985/10307
Bubble effect on the structures of weakly turbulent couette taylor flow
MEHEL, Amine; DJERIDI, Henda; GABILLET, Céline
In industrial applications, rotating flows have been recognized to enhance mixing and transfer properties. Moreover, bubbly flows are also used to improve transfers. Therefore, it is interesting to study the effects of the dispersed phase on the structure of a Couette Taylor flow. Experiments are conducted for the quasi-periodic (Ta=780) and the weakly turbulent (Ta=1000) flow regimes. Bubbles (0.035 times as small as the gap) are generated by agitation of the upper free surface (ventilated flow). Larger bubbles (0.15 times as small as the gap) are generated by injection at the bottom of the apparatus and by applying a pressure drop (gaseous-cavitating flow). Void fraction, bubble size and velocity, as well as axial and azimuthal velocity components of the liquid are investigated. The bubble location in the gap clearly depends on the bubble size. For alpha>0.1%, there is evidence of bubble induced modifications of axial transfers and wall shear stress, the observed trends being different according to the bubble location in the gap.
Sun, 01 Jan 2006 00:00:00 GMThttp://hdl.handle.net/10985/103072006-01-01T00:00:00ZMEHEL, AmineDJERIDI, HendaGABILLET, CélineIn industrial applications, rotating flows have been recognized to enhance mixing and transfer properties. Moreover, bubbly flows are also used to improve transfers. Therefore, it is interesting to study the effects of the dispersed phase on the structure of a Couette Taylor flow. Experiments are conducted for the quasi-periodic (Ta=780) and the weakly turbulent (Ta=1000) flow regimes. Bubbles (0.035 times as small as the gap) are generated by agitation of the upper free surface (ventilated flow). Larger bubbles (0.15 times as small as the gap) are generated by injection at the bottom of the apparatus and by applying a pressure drop (gaseous-cavitating flow). Void fraction, bubble size and velocity, as well as axial and azimuthal velocity components of the liquid are investigated. The bubble location in the gap clearly depends on the bubble size. For alpha>0.1%, there is evidence of bubble induced modifications of axial transfers and wall shear stress, the observed trends being different according to the bubble location in the gap.Numerical simulations of drag modulation by microbubbles in a turbulent Taylor-Couette flow
http://hdl.handle.net/10985/8695
Numerical simulations of drag modulation by microbubbles in a turbulent Taylor-Couette flow
CHOUIPPE, Agathe; CLIMENT, Eric; LEGENDRE, Dominique; GABILLET, Céline
The aim of our study is to investigate numerically the interaction between a dispersed phase composed of microbubbles and a turbulent Taylor-Couette flow (flow within the gap between two cylinders). We use the Euler-Lagrange approach based on Direct Numerical Simulation of the continuous phase flow equations and a Lagrangian tracking for the dispersed phase. Each bubble trajectory is calculated by integrating the force balance equation accounting for buoyancy, drag, added-mass, pressure gradient, and the lift forces. The numerical method has been adapted in order to take into account the feed-back effect of the dispersed bubbles on the carrying flow. Our approach is based on local volume average of the two-phase Navier-Stokes equations. Local and temporal variations of the bubble concentration and momentum source terms are accounted for in mass and momentum balance equations. A number of reference cases have been tested to validate the modelling approach and its numerical implementation. Then, our previous study of bubble dispersion has been extended to two-way coupling simulations of turbulent Taylor-Couette flows (only inner cylinder is rotating). Modulation of the drag will be discussed for different geometries, Reynolds numbers and bubble sizes. The results show that near-wall turbulent structures are modified by the presence of bubbles.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/86952013-01-01T00:00:00ZCHOUIPPE, AgatheCLIMENT, EricLEGENDRE, DominiqueGABILLET, CélineThe aim of our study is to investigate numerically the interaction between a dispersed phase composed of microbubbles and a turbulent Taylor-Couette flow (flow within the gap between two cylinders). We use the Euler-Lagrange approach based on Direct Numerical Simulation of the continuous phase flow equations and a Lagrangian tracking for the dispersed phase. Each bubble trajectory is calculated by integrating the force balance equation accounting for buoyancy, drag, added-mass, pressure gradient, and the lift forces. The numerical method has been adapted in order to take into account the feed-back effect of the dispersed bubbles on the carrying flow. Our approach is based on local volume average of the two-phase Navier-Stokes equations. Local and temporal variations of the bubble concentration and momentum source terms are accounted for in mass and momentum balance equations. A number of reference cases have been tested to validate the modelling approach and its numerical implementation. Then, our previous study of bubble dispersion has been extended to two-way coupling simulations of turbulent Taylor-Couette flows (only inner cylinder is rotating). Modulation of the drag will be discussed for different geometries, Reynolds numbers and bubble sizes. The results show that near-wall turbulent structures are modified by the presence of bubbles.Mitigation of underwater explosion effects by bubble curtains : experiments and modelling
http://hdl.handle.net/10985/8696
Mitigation of underwater explosion effects by bubble curtains : experiments and modelling
CROCI, Kilian; ARRIGONI, Michel; BOYCE, P; GRANDJEAN, Hervé; JACQUES, Nicolas; KERAMPRAN, Steven; GABILLET, Céline
Mine fields and UneXploded Ordnances (UXO) become a danger regarding maritime activities. Since UXOs are strongly affected by marine corrosion after decades, they cannot be handled safely. A safe solution to get rid of them would be to explode them in their locations. However, this method generates noise pollution and damaging shock waves. Mitigation of shocks and noises is made possible by the use of a bubble curtain set around the explosive charge. Physical aspects of shock propagation in bubbly flows have been the subject of numerous investigations in the past decades and theoretical models of aerated liquids now reproduce main shock features with acceptable accuracy in the case of a uniform distribution of bubbles of the same size. However, the bubble distribution obtained by air blown in a porous pipe is far to be monodisperse. So the modeling of the interaction of a shock wave with a polydisperse medium still remains a challenge. In the present study, the transmission of a shock wave propagating through a bubble curtain is investigated experimentally on a water filled tank. A microporous pipe, connected to a compressed air supply system and a flowmeter, is placed on the floor in the tank. A dual-tip fiber optical probe is used to measure the gas fraction distribution, bubble rising velocity and bubble size distribution in the curtain. A calibrated shock wave is generated by plate impact, upstream of the bubble curtain, and recorded downstream with a hydrophone. The mitigation of the pressure peak by the bubbly medium is evidenced by recorded pressure signals with and without bubble curtain. Experimental gas fraction profiles and bubble size distributions, measured in the bubble curtains, are finally used as input parameters in the numerical model developed by Grandjean et al. (2011). This numerical model enables prediction of shock wave mitigation and allows calibrating a suitable bubble curtain.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/10985/86962014-01-01T00:00:00ZCROCI, KilianARRIGONI, MichelBOYCE, PGRANDJEAN, HervéJACQUES, NicolasKERAMPRAN, StevenGABILLET, CélineMine fields and UneXploded Ordnances (UXO) become a danger regarding maritime activities. Since UXOs are strongly affected by marine corrosion after decades, they cannot be handled safely. A safe solution to get rid of them would be to explode them in their locations. However, this method generates noise pollution and damaging shock waves. Mitigation of shocks and noises is made possible by the use of a bubble curtain set around the explosive charge. Physical aspects of shock propagation in bubbly flows have been the subject of numerous investigations in the past decades and theoretical models of aerated liquids now reproduce main shock features with acceptable accuracy in the case of a uniform distribution of bubbles of the same size. However, the bubble distribution obtained by air blown in a porous pipe is far to be monodisperse. So the modeling of the interaction of a shock wave with a polydisperse medium still remains a challenge. In the present study, the transmission of a shock wave propagating through a bubble curtain is investigated experimentally on a water filled tank. A microporous pipe, connected to a compressed air supply system and a flowmeter, is placed on the floor in the tank. A dual-tip fiber optical probe is used to measure the gas fraction distribution, bubble rising velocity and bubble size distribution in the curtain. A calibrated shock wave is generated by plate impact, upstream of the bubble curtain, and recorded downstream with a hydrophone. The mitigation of the pressure peak by the bubbly medium is evidenced by recorded pressure signals with and without bubble curtain. Experimental gas fraction profiles and bubble size distributions, measured in the bubble curtains, are finally used as input parameters in the numerical model developed by Grandjean et al. (2011). This numerical model enables prediction of shock wave mitigation and allows calibrating a suitable bubble curtain.Open ocean regimes of relative dispersion
http://hdl.handle.net/10985/10165
Open ocean regimes of relative dispersion
OLLITRAULT, Michel; COLIN DE VERDIERE, Alain; GABILLET, Céline
As two fluid particles separate in time, the entire spectrum of eddy motions is being sampled from the smallest to the largest scales. In large-scale geophysical systems for which the Earth rotation is important, it has been conjectured that the relative diffusivity should vary respectively as D2 and D4/3 for distances respectively smaller and larger than a well-defined forcing scale of the order of the internal Rossby radius (with D the r.m.s. separation distance). Particle paths data from a mid-latitude float experiment in the central part of the North Atlantic appear to support these statements partly: two particles initially separated by a few km within two distinct clusters west and east of the mid-Atlantic ridge, statistically dispersed following a Richardson regime (D2∼t3 asymptotically) for r.m.s. separation distances between 40 and 300 km, in agreement with a D4/3 law. At early times, and for smaller separation distances, an exponential growth, in agreement with a D2 law, was briefly observed but only for the eastern cluster (with an e-folding time around 6 days). After a few months or separation distances greater than 300 km, the relative dispersion slowed down naturally to the Taylor absolute dispersion regime.
Sat, 01 Jan 2005 00:00:00 GMThttp://hdl.handle.net/10985/101652005-01-01T00:00:00ZOLLITRAULT, MichelCOLIN DE VERDIERE, AlainGABILLET, CélineAs two fluid particles separate in time, the entire spectrum of eddy motions is being sampled from the smallest to the largest scales. In large-scale geophysical systems for which the Earth rotation is important, it has been conjectured that the relative diffusivity should vary respectively as D2 and D4/3 for distances respectively smaller and larger than a well-defined forcing scale of the order of the internal Rossby radius (with D the r.m.s. separation distance). Particle paths data from a mid-latitude float experiment in the central part of the North Atlantic appear to support these statements partly: two particles initially separated by a few km within two distinct clusters west and east of the mid-Atlantic ridge, statistically dispersed following a Richardson regime (D2∼t3 asymptotically) for r.m.s. separation distances between 40 and 300 km, in agreement with a D4/3 law. At early times, and for smaller separation distances, an exponential growth, in agreement with a D2 law, was briefly observed but only for the eastern cluster (with an e-folding time around 6 days). After a few months or separation distances greater than 300 km, the relative dispersion slowed down naturally to the Taylor absolute dispersion regime.Contribution to the MHD modeling in low speed radial flux AC machines with air-gaps filled with conductive fluids
http://hdl.handle.net/10985/8702
Contribution to the MHD modeling in low speed radial flux AC machines with air-gaps filled with conductive fluids
MENANA, Hocine; CHARPENTIER, Jean-Frederic; GABILLET, Céline
This work deals with the modeling of the magnetohydrodynamic (MHD) phenomena in the air-gaps of low speed radial flux AC electrical machines filled with incompressible and electrically conductive fluids. The proposed model concerns laminar flows and it is based on a weak MHD coupling at the steady state regimes. The MHD power losses are evaluated and discussed. The model is easy to implement and could be a useful tool for the design and the optimization. An application to marine current turbine is considered.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/10985/87022014-01-01T00:00:00ZMENANA, HocineCHARPENTIER, Jean-FredericGABILLET, CélineThis work deals with the modeling of the magnetohydrodynamic (MHD) phenomena in the air-gaps of low speed radial flux AC electrical machines filled with incompressible and electrically conductive fluids. The proposed model concerns laminar flows and it is based on a weak MHD coupling at the steady state regimes. The MHD power losses are evaluated and discussed. The model is easy to implement and could be a useful tool for the design and the optimization. An application to marine current turbine is considered.Experimental Study of the Flow in a Compact Heat Exchanger Channel with Embossed-type Vortex Generators
http://hdl.handle.net/10985/9495
Experimental Study of the Flow in a Compact Heat Exchanger Channel with Embossed-type Vortex Generators
DUPONT, Frédéric; BOT, Patrick; GABILLET, Céline
The isothermal flow in a model channel of plate-fin heat exchanger with periodically arranged embossed-like vortex generators is investigated. Velocity measurements are performed by LDA in the transitional regime (Reynolds number from 1000 up to 5000). Strong longitudinal vortices are observed downstream of each vortex generator. The vortex roll-up process is highlighted by the evolution of the velocity vector field in the cross section of the flow. The modifications of the vortex characteristics after successively encountered generators are investigated. This work shows most of the flow features which are known to produce heat transfer enhancement, and shows that these smooth shaped vortex generators are very promising for enhanced heat exchangers.
Wed, 01 Jan 2003 00:00:00 GMThttp://hdl.handle.net/10985/94952003-01-01T00:00:00ZDUPONT, FrédéricBOT, PatrickGABILLET, CélineThe isothermal flow in a model channel of plate-fin heat exchanger with periodically arranged embossed-like vortex generators is investigated. Velocity measurements are performed by LDA in the transitional regime (Reynolds number from 1000 up to 5000). Strong longitudinal vortices are observed downstream of each vortex generator. The vortex roll-up process is highlighted by the evolution of the velocity vector field in the cross section of the flow. The modifications of the vortex characteristics after successively encountered generators are investigated. This work shows most of the flow features which are known to produce heat transfer enhancement, and shows that these smooth shaped vortex generators are very promising for enhanced heat exchangers.The influence of aeration and compressibility on slamming loads during cone water entry
http://hdl.handle.net/10985/11777
The influence of aeration and compressibility on slamming loads during cone water entry
ELHIMER, Mehdi; JACQUES, Nicolas; EL MALKI ALAOUI, Aboulghit; GABILLET, Céline
The problem of the impact between a rigid body and a gas-liquid mixture is relevant to various engineering applications, including the design of breakwaters and LNG containers. In the present study, the specific problem of the impact of a rigid cone upon the surface of an aerated liquid is investigated. Numerical simulations of water entry of cones with different dead-rise angles (7° and 15°) were performed using an explicit finite element method. The air-water mixture is modelled as a homogeneous fluid with a specific equation of state. In addition, experimental tests of the impact of a cone with a dead-rise angle of 7° on the surface of bubbly water were performed. The air volume fraction was measured prior to the impact tests using optical probes technique, and the instantaneous impact force on the cone was measured using strain gauges. The results highlight a significant reduction of the impact load with the increase of the air volume fraction. Moreover, the numerical results show that this reduction is also dependent on the impact velocity. This phenomenon is found to be related to the nonlinearity of the equation of state of the air-water mixture.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10985/117772017-01-01T00:00:00ZELHIMER, MehdiJACQUES, NicolasEL MALKI ALAOUI, AboulghitGABILLET, CélineThe problem of the impact between a rigid body and a gas-liquid mixture is relevant to various engineering applications, including the design of breakwaters and LNG containers. In the present study, the specific problem of the impact of a rigid cone upon the surface of an aerated liquid is investigated. Numerical simulations of water entry of cones with different dead-rise angles (7° and 15°) were performed using an explicit finite element method. The air-water mixture is modelled as a homogeneous fluid with a specific equation of state. In addition, experimental tests of the impact of a cone with a dead-rise angle of 7° on the surface of bubbly water were performed. The air volume fraction was measured prior to the impact tests using optical probes technique, and the instantaneous impact force on the cone was measured using strain gauges. The results highlight a significant reduction of the impact load with the increase of the air volume fraction. Moreover, the numerical results show that this reduction is also dependent on the impact velocity. This phenomenon is found to be related to the nonlinearity of the equation of state of the air-water mixture.Effect of bubble’s arrangement on the viscous torque in bubbly Taylor- Couette flow
http://hdl.handle.net/10985/9419
Effect of bubble’s arrangement on the viscous torque in bubbly Taylor- Couette flow
NDONGO FOKOUA, Georges; AUBERT, Adrien; COLIN, Catherine; GABILLET, Céline
An experimental investigation of the interactions between bubbles, coherent motion and viscous drag in a Taylor-Couette flow with the outer cylinder at rest is presented. The cylinder radii ratio η is 0.91. Bubbles are injected inside the gap through a needle at the bottom of the apparatus. Different bubbles sizes are investigated (ratio between the bubble diameter and the gap width ranges from 0.05 to 0.125) for very small void fraction (α<=0.23%). Different flow regimes are studied corresponding to Reynolds number Re based on the gap width and velocity of the inner cylinder, ranging from 600 to 20000. Regarding these Re values, Taylor vortices are persistent leading to an axial periodicity of the flow. A detailed characterization of the vortices is performed for the single-phase flow. The experiment also develops bubbles tracking in a meridian plane and viscous torque of the inner cylinder measurements. The findings of this study show evidence of the link between bubbles localisation, Taylor vortices and viscous torque modifications. We also highlight two regimes of viscous torque modification and various types of bubbles arrangements, depending on their size and on the Reynolds number. Bubbles can have a sliding and wavering motion near the inner cylinder and be either captured by the Taylor vortices or by the outflow areas near the inner cylinder. For small buoyancy effect, bubbles are trapped, leading to an increase of the viscous torque. When buoyancy induced bubbles motion is increased by comparison to the coherent motion of the liquid, a decrease in the viscous torque is rather observed. The type of bubble arrangement is parameterized by the two dimensionless parameters C and H introduced by Climent et al. [E. Climent, M. Simonnet and J. Magnaudet, Phys. Fluids 19, 083301(2007)]. Phase diagrams summarizing the various types of bubbles arrangements, viscous torque modifications and axial wavelength evolution are built.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/94192015-01-01T00:00:00ZNDONGO FOKOUA, GeorgesAUBERT, AdrienCOLIN, CatherineGABILLET, CélineAn experimental investigation of the interactions between bubbles, coherent motion and viscous drag in a Taylor-Couette flow with the outer cylinder at rest is presented. The cylinder radii ratio η is 0.91. Bubbles are injected inside the gap through a needle at the bottom of the apparatus. Different bubbles sizes are investigated (ratio between the bubble diameter and the gap width ranges from 0.05 to 0.125) for very small void fraction (α<=0.23%). Different flow regimes are studied corresponding to Reynolds number Re based on the gap width and velocity of the inner cylinder, ranging from 600 to 20000. Regarding these Re values, Taylor vortices are persistent leading to an axial periodicity of the flow. A detailed characterization of the vortices is performed for the single-phase flow. The experiment also develops bubbles tracking in a meridian plane and viscous torque of the inner cylinder measurements. The findings of this study show evidence of the link between bubbles localisation, Taylor vortices and viscous torque modifications. We also highlight two regimes of viscous torque modification and various types of bubbles arrangements, depending on their size and on the Reynolds number. Bubbles can have a sliding and wavering motion near the inner cylinder and be either captured by the Taylor vortices or by the outflow areas near the inner cylinder. For small buoyancy effect, bubbles are trapped, leading to an increase of the viscous torque. When buoyancy induced bubbles motion is increased by comparison to the coherent motion of the liquid, a decrease in the viscous torque is rather observed. The type of bubble arrangement is parameterized by the two dimensionless parameters C and H introduced by Climent et al. [E. Climent, M. Simonnet and J. Magnaudet, Phys. Fluids 19, 083301(2007)]. Phase diagrams summarizing the various types of bubbles arrangements, viscous torque modifications and axial wavelength evolution are built.Time Resolved Two Dimensional X-Ray Densitometry of a Two Phase Flow Downstream of a Ventilated Cavity
http://hdl.handle.net/10985/8674
Time Resolved Two Dimensional X-Ray Densitometry of a Two Phase Flow Downstream of a Ventilated Cavity
MAKIHARJU, Simo A; PAIK, Bu-Geun; CHANG, Natasha A; PERLIN, Marc; CECCIO, Steven L; GABILLET, Céline
To measure the void fraction distribution in gas-liquid flows, a two-dimensional x-ray densitometry system was developed. This system is capable of acquiring a two-dimensional projection with a 225 cm2 area of measurement through 21 cm of water. The images can be acquired at rates on the order of 1 kHz. Common sources of error in x-ray imaging, such as x-ray scatter, image distortion, veiling glare, and beam hardening were considered, and mitigated. The measured average void fraction was compared success fully to that of a phantom target and found to be within 1%. To evaluate the performance of the new system, the flow in and downstream of a ventilated nominally two-dimensional partial cavity was investigated and compared to measurements from dual tip fiber optical probes and high speed video. The measurements were found to have satisfactory agreement for void fractions above 5% of the selected void fraction measurement range.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/86742013-01-01T00:00:00ZMAKIHARJU, Simo APAIK, Bu-GeunCHANG, Natasha APERLIN, MarcCECCIO, Steven LGABILLET, CélineTo measure the void fraction distribution in gas-liquid flows, a two-dimensional x-ray densitometry system was developed. This system is capable of acquiring a two-dimensional projection with a 225 cm2 area of measurement through 21 cm of water. The images can be acquired at rates on the order of 1 kHz. Common sources of error in x-ray imaging, such as x-ray scatter, image distortion, veiling glare, and beam hardening were considered, and mitigated. The measured average void fraction was compared success fully to that of a phantom target and found to be within 1%. To evaluate the performance of the new system, the flow in and downstream of a ventilated nominally two-dimensional partial cavity was investigated and compared to measurements from dual tip fiber optical probes and high speed video. The measurements were found to have satisfactory agreement for void fractions above 5% of the selected void fraction measurement range.Numerical simulation of bubble dispersion in turbulent Taylor-Couette flow
http://hdl.handle.net/10985/8678
Numerical simulation of bubble dispersion in turbulent Taylor-Couette flow
CHOUIPPE, Agathe; CLIMENT, Eric; LEGENDRE, Dominique; GABILLET, Céline
We investigate bubble dispersion in turbulent Taylor-Couette flow. The aim of this study is to describe the main mechanisms yielding preferential bubble accumulation in near-wall structures of the flow. We first proceed to direct numerical simulation of Taylor-Couette flows for three different geometrical configurations (three radius ratios η = R 1/R 2: η = 0.5, η = 0.72, and η = 0.91 with the outer cylinder at rest) and Reynolds numbers corresponding to turbulent regime ranging from 3000 to 8000. The statistics of the flow are discussed using two different averaging procedures that permit to characterize the mean azimuthal velocity, the Taylor vortices contribution and the small-scale turbulent fluctuations. The simulations are compared and validated with experimental and numerical data from literature. The second part of this study is devoted to bubble dispersion. Bubble accumulation is analyzed by comparing the dispersion obtained with the full turbulent flow field to bubble dispersion occurring at lower Reynolds numbers in previous works. Several patterns of preferential accumulation of bubbles have been observed depending on bubble size and the effect of gravity. For the smaller size considered, bubbles disperse homogeneously throughout the gap, while for the larger size they accumulate along the inner wall for the large gap width (η = 0.5). Varying the intensity of buoyancy yields complex evolution of the bubble spatial distribution. For low gravity effect, bubble entrapment is strong leading to accumulation along the inner wall in outflow regions (streaks of low wall shear stress). When buoyancy effect dominates on vortex trapping, bubbles rise through the vortices, while spiral patterns stretched along the inner cylinder are clearly identified. Force balance is analyzed to identify dominating forces leading to this accumulation and accumulation patterns are compared with previous experiments.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/10985/86782014-01-01T00:00:00ZCHOUIPPE, AgatheCLIMENT, EricLEGENDRE, DominiqueGABILLET, CélineWe investigate bubble dispersion in turbulent Taylor-Couette flow. The aim of this study is to describe the main mechanisms yielding preferential bubble accumulation in near-wall structures of the flow. We first proceed to direct numerical simulation of Taylor-Couette flows for three different geometrical configurations (three radius ratios η = R 1/R 2: η = 0.5, η = 0.72, and η = 0.91 with the outer cylinder at rest) and Reynolds numbers corresponding to turbulent regime ranging from 3000 to 8000. The statistics of the flow are discussed using two different averaging procedures that permit to characterize the mean azimuthal velocity, the Taylor vortices contribution and the small-scale turbulent fluctuations. The simulations are compared and validated with experimental and numerical data from literature. The second part of this study is devoted to bubble dispersion. Bubble accumulation is analyzed by comparing the dispersion obtained with the full turbulent flow field to bubble dispersion occurring at lower Reynolds numbers in previous works. Several patterns of preferential accumulation of bubbles have been observed depending on bubble size and the effect of gravity. For the smaller size considered, bubbles disperse homogeneously throughout the gap, while for the larger size they accumulate along the inner wall for the large gap width (η = 0.5). Varying the intensity of buoyancy yields complex evolution of the bubble spatial distribution. For low gravity effect, bubble entrapment is strong leading to accumulation along the inner wall in outflow regions (streaks of low wall shear stress). When buoyancy effect dominates on vortex trapping, bubbles rise through the vortices, while spiral patterns stretched along the inner cylinder are clearly identified. Force balance is analyzed to identify dominating forces leading to this accumulation and accumulation patterns are compared with previous experiments.