Publications Scientifiques
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Item Study of nanofluids cavitating flow through a venturi using computational fluid dynamics code(Publishing House of the Romanian Academy, 2025) Benghalia I.; Nehaoua N.; Zamoum M.; Ami I.In this work, we conducted a numerical study of cavitating nanofluid flow through a Venturi. The objective is to investigate the influence of nanoparticles in the base fluid on the cavitation phenomenon. The computational fluid dynamics code (CFD) was selected with a cavitation model. The mixture model for multiphase flow and the k-ω SST turbulence model were adopted. Three fluids were chosen: water, Cu/water and TiO2/water with different volume franctions of nanoparticle (0%, 10% 20%, 30%). The simulation was conducted with inlet and outlet pressures set at 700 kPa and atmosphere pressure respectively. The numerical results are compared with the previous experimental and numerical data for flow without nanoparticle. The obtained results found that, the presence of the nanoparticles in the base fluid lead to a slight increase in the static pressure, the position of pressure recovery a significant decrease in fluid velocity and an increase in the vapor fraction formation in the flow. Also, the increase of the nanoparticle volume fractions φ results a decrease in the pressure recovery position, fluid velocity and an increase in the vapor fraction formation. Therefore, the presence of nanoparticles in the base fluid promotes the phenomenon of cavitationItem Study of nanofluids cavitating flow through a venturi using computational fluid dynamics code(2025) Benghalia, Imen; Nehaoua, N.; Zamoum, M.; AMI, I.In this work, we conducted a numerical study of cavitating nanofluid flow through a Venturi. The objective is to investigate the influence of nanoparticles in the base fluid on the cavitation phenomenon. The computational fluid dynamics code (CFD) was selected with a cavitation model. The mixture model for multiphase flow and the k-ω SST turbulence model were adopted. Three fluids were chosen: water, Cu/water and TiO2/water with different volume franctions of nanoparticle (0%, 10% 20%, 30%) . The simulation was conducted with inlet and outlet pressures set at 700 kPa and atmosphere pressure respectively. The numerical results are compared with the previous experimental and numerical data for flow without nanoparticle. The obtained results found that, the presence of the nanoparticles in the base fluid lead to a slight increase in the static pressure, the position of pressure recovery a significant decrease in fluid velocity and an increase in the vapor fraction formation in the flow. Also, the increase of the nanoparticle volume fractions φ results a decrease in the pressure recovery position, fluid velocity and an increase in the vapor fraction formation. Therefore, the presence of nanoparticles in the base fluid promotes the phenomenon of cavitation.Item Comparative analysis on heat transfer, between a steady and oscillating jet in a cavity(Inderscience Publishers, 2024) Iachachene, Farida; Mataoui, AminaThis paper numerically investigates the cooling of a heated rectangular cavity by a cold slot jet. The study aims to examine the effect of the jet location inside the cavity (Lf and Lh) and Reynolds number on heat transfer, using URANS turbulence modelling. Different flow behaviours, including oscillatory and steady flows, are generated depending on the jet location inside the cavity. The study identifies and discusses the optimal jet locations for achieving optimal cavity cooling. The results indicate that the lateral placement of the jet has a negligible effect on heat transfer across all cavity walls. Additionally, oscillatory flow consistently expands the heat exchange zone along all three walls, resulting in a wider effective exchange area compared to steady flow conditions. The study proposes optimised jet positions within the cavity for specific wall cooling requirements. By considering the optimal combination of jet height and impinging distance, the cooling performance can be optimised.Item Split Control Wind Turbine Airfoil noise with CFD and Acoustic Analogies(Isfahan University of Technology, 2024) Khenfous, Soumia; Maizi, Mohamed; Zamoum, MohammedThis research aims to investigate the impact of a split airfoil on noise emissions from a horizontal-axis wind turbine. The objective is to comprehensively understand the airflow patterns around the airfoil to reduce noise emissions. The study rigorously examines a range of angles of attack, from 0° to 25°, for both the original airfoil and the airfoil with a split, using advanced computational aerodynamics coupled with analog acoustic analysis. The methodology involves two-dimensional flow simulations with Delayed Detached Eddy Simulation based on the Spalart-Allmaras model, enabling precise near-field flow calculations around the airfoil. Additionally, far-field noise predictions, employing the Ffowcs Williams and Hawkings analogy based on simulated sources, reveal the efficacy of the split airfoil design. Results indicate that the split airfoil design effectively reduces noise emissions across various angles of attack. These reductions translate into a significant decrease in the Overall Sound Pressure Level, ranging from 14% to 19%, and remarkable Sound Pressure Level reductions between 12% and 60% across diverse frequencies, showcasing substantial noise improvements in various frequency ranges.Item Comparative Assessment of Non-newtonian Single-Phase and Two-Phase Approaches for Numerical Studies of Centrifugal Pumps Handling Emulsion(Springer Nature, 2024) Achour, Lila; Specklin, Mathieu; Asuaje, Miguel; Kouidri, Smaine; Belaidi, IdirComputational Fluid Dynamics is commonly employed to assess the effect of oil-water emulsions on pump performance, usually using two-phase models. However, these models often neglect the emulsion’s non-Newtonian behavior, despite its known experimental significance in enhancing pump performance. This study attempts to evaluate both single-phase non-Newtonian and two-phase approaches to model emulsion flow within centrifugal pumps. The non-Newtonian single-phase and several two-phase models are evaluated by comparing the predicted pump heads with experimental data of a multistage pump from the literature. The findings show that the non-Newtonian single-phase model generally provides better agreement with experimental measurements, particularly for emulsions with low dispersed phase fractions. Nevertheless, for emulsions with a high dispersed phase fraction (≈ 50%), the difference between the two approaches is insignificant. Thus, due to the lack of a universal multiphase model for emulsion simulation, the non-Newtonian single-phase model can serve as a viable alternative, overcoming the limitations of two-phase approaches in simulating complex multiphase fluid systems.Item Numerical study of the performance loss of a centrifugal pump carrying emulsion(2021) Achour, Lila; Mathieu, Specklin; Belaidi, Idir; Kouidri, SmaineThe performance and hydrodynamic behavior of cen- trifugal pumps when handling two-phase liquid-liquid flow and emulsion remain relatively unexplored, al- though they are of fundamental importance in optimiz- ing the operating conditions of these pumps. Hence, this study aims at investigating the performance degra- dation of a centrifugal pump under emulsion flow by combined means of analytical and computational fluid dynamic (CFD) models. The analytical approach is based on internal energy loss equations while the CFD approach models the emulsion as a continuous and ho- mogeneous single-phase fluid exhibiting shear thinning behavior. The results give a good insight into the per- formance degradation of such a system, especially at the best efficiency point (BEP).Item Numerical assessment of the hydrodynamic behavior of a volute centrifugal pump handling emulsion(MDPI, 2022) Achour, Lila; Specklin, Mathieu; Belaidi, Idir; Kouidri, SmaineAlthough emulsion pumping is a subject of growing interest, a detailed analysis of the fluid dynamic phenomena occurring inside these machines is still lacking. Several computational investigations have been conducted to study centrifugal pumps carrying emulsion by analyzing their overall performance, but no studies involved the rheological behavior of such fluids. The purpose of this study is to perform a computational analysis of the performance and flow characteristics of a centrifugal pump with volute handling emulsions and oil–water mixtures at different water cuts modeled as a shear-thinning non-Newtonian fluid. The studied pump consists of a five-bladed backward curved impeller and a volute and has a specific speed of 32 (metric units). The rheological properties of the mixtures studied were measured experimentally under a shear rate ranging from 1 s−1 to 3000 s−1 and were fitted to conventional Cross and Carreau effective viscosity models. Numerical results showed the flow topology in the pump is directly related to the viscosity plateau of the pseudoplastic behavior of emulsions. The viscosity plateau governs pump performance by influencing the loss mechanisms that occur within the pump. The larger the ν∞, the less recirculation loss the fluid experiences, and conversely, the smaller the value of ν0, the less friction loss the fluid experiencesItem Modeling surge pressures during tripping operations in eccentric annuli(Elsevier, 2021) Belimane, Zakarya; Hadjadj, Ahmed; Ferroudji, Hicham; Rahman, Mohammad Azizur; Qureshi, M. FahedThe aim of this paper is to present a new numerical model to study the drilling fluid flow through eccentric annulus during tripping operations and to investigate the effect of the eccentricity on the annular velocity and apparent viscosity profiles. Many published works studied surge and swab phenomenon using simplified numerical models that do not consider the azimuthal variation of the shear stress in the eccentric annuli. In this paper, the developed numerical model takes into consideration this variation. Non-orthogonal, curvilinear coordinates were used to generate a body-fitted elliptic mesh that maps the irregular complicated eccentric annulus into a simple rectangle where flow equations can be discretized using the finite difference method then solved numerically. Besides, a commercial software (ANSYS Fluent 19R3) was used to support the findings of the numerical model. Results of these models were validated against the experimental data from literature where good agreement was observed with an average relative error of 2.6%, 3.8%, and 6.8% for the three Herschel-Bulkley fluids studied in the eccentric case. The profiles of velocity and viscosity were plotted, the contours showed that we cannot use an average velocity or a single value for the apparent viscosity to describe the drilling fluid flowing through an eccentric annulus, but, the whole profile should be used, instead. The developed numerical model was used in a parametric study to investigate the effect of eccentricity on the relationship between surge pressure and the relevant drilling parameters namely tripping velocity, annular geometry, and fluid rheological properties. The results showed that the eccentricity decreases the surge pressure independently of the previous parameters and that the rate of decrease varies from one parameter to another. The outcome of this parametric study was used to construct a surrogate model using Random Forest Regressor. Predictions from the surrogate model fit the numerical data very well with R-squared of 0.99 and 0.97 for training and test data, respectivelyItem The effect of orbital motion and eccentricity of drill pipe on pressure gradient in eccentric annulus flow with Newtonian and non-Newtonian fluids(Inderscience, 2020) Ferroudji, Hicham; Hadjadj, Ahmed; Ntow Ofei, Titus; Rahman, Mohammad AzizurThe correct prediction of the pressure gradient is the fundamental parameter to establish an effective hydraulics program, which enables an optimised drilling process. In the present work, the effect of the orbital motion of the drill pipe on the pressure drop in an eccentric annulus flow with Newtonian and non-Newtonian fluids is studied numerically for both laminar and turbulent regimes using finite volume method (FVM). Furthermore, the effect of eccentricity when the inner pipe makes an orbital motion is evaluated. Different behaviours are observed in laminar and turbulent regimes. In the laminar regime, the simulation results showed that an increase of the orbital motion speed causes a considerable increment of the pressure gradient for the Newtonian fluid. For the power-law, non-Newtonian fluid in the laminar regime, on the contrary, a decrease of the pressure gradient is observed due to the shear-thinning effect. In the turbulent regime the mentioned trends are predicted to be much weaker. As eccentricity increases, the pressure drop of the non-Newtonian fluid decreases with a more pronounced diminish in pressure drop when the drill pipe is in orbital motion for both laminar and turbulent flow regimes.Item Study of Ostwald-de Waele fluid flow in an elliptical annulus using the slot model and the CFD approach(Taylor & Francis, 2020) Ferroudji, Hicham; Hadjadj, A.; Rahman, M.A.; Hassan, I.; Maheshwari, P.; Odan, M.A.Among consequences that can be induced by a non-uniform distribution of the stress and other causes during the drilling process is the elliptical shape of the well and consideration of this effect would improve the accuracy of the drilling fluid hydrodynamics prediction. In the present work, the elliptical shape of the annular space is simplified to apply the slot model taking into account the rotation of the inner cylinder. Moreover, the Slot model results are compared with the experimental data, as well as, with the CFD outcomes where a reasonable concordance is observed, especially for low ratios of the major and minor semi-axis. Also, the CFD results are validated with the experimental data from the flow loop setup. We concluded that the increase of the major and minor semi-axis ratio of the elliptical annulus results in a linear increase of the Ostwald-de Waele frictional pressure loss in the laminar regime for all considered rotation speeds of the inner cylinder. In addition, the increase of the eccentricity from 0 to 0.75 has a positive effect where the frictional pressure loss is decreased by almost 28% for all rotation speeds for the elliptical annulus ((Formula presented.))