Browsing by Author "Benbrik, Abderahmane"

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Buoyancy ratio effects on coupled radiation and double-diffusive convection in non-gray air-H2O mixtures
(IEEE, 2015) Laouar-Meftah, Siham; Benbrik, Abderahmane; Cherifi, M.; Lemonnier, D.
Comparative study of radiative effects on double diffusive convection in nongray Air-CO2 mixtures in cooperating and opposing flow
(Hindawi Publishing Corporation, 2015) Laouar-Meftah, Siham; Lemonnier, Denis; Saury, Didier; Benbrik, Abderahmane; Cherifi, Mohamed
This study analyses the effects of nongray gas radiation on double diffusive convection, in a square differentially heated cavity filled with air-CO2 mixtures, when the buoyancy forces (thermal and mass) are cooperating or opposing. The radiative source term in the energy equation is evaluated by the discrete ordinate method (solving the radiative transfer equation) and the SLW spectral model (accounting for real radiative properties of absorbing species). Here, gas absorption varies with the local temperature and concentration of pollutant, which induces a strong direct coupling between the concentration and thermal fields that would not exist with gray gas. Simulations are performed at different concentrations of CO2 corresponding to different flow regimes (thermal, transitional, and mass). Results show the following: (i) in cooperating flow, radiation modifies essentially the heat transfer and the characteristics of temperature and concentration fields; (ii) in opposing flow, radiation effects are more important and depend on the nature of the flow regime
Contribution to fire protection of the LNG storage tank using water curtain
(IASKS, 2011) Benbrik, Abderahmane; Cherifi, M.; Meftah, S.; Khelifi, M.S.; Sahnoune, K.
In the early years of the oil and gas industry, fire in storage tanks was the common root of most of the incidents. One technique to protect the integrity of neighboring tanks is the water spray curtain, which can provide thermal shielding against fire. This study presents a numerical simulation of radiative heat transfer by the Mont Carlo method through a semitransparent medium (water spray curtain) containing water droplets and gas for the design of an effective thermal shielding system to protect LNG (or combustibles) storage tank from fire. This model will allow us to calculate exactly the attenuation factor of the water curtain as a function of its thickness, density and the size of water droplets. The medium is considered as a non grey, absorbing and anisotropically scattering. The spectral behavior of the medium is taken into account by the Mie theory and the SNB model applied respectively to water droplets and gas (H2O, CO and CO2). The calculated results are satisfactorily in agreement with the experimental data
Coupled radiation and double diffusive convection in nongray Air-CO2 and Air-H2O mixtures in cooperating situations
(Taylor & Francis, 2009) Meftah, S.; Lemonnier, D.; Benbrik, Abderahmane; Ibrahim, A.
This study highlights the interaction between gas radiation and double diffusive convection in cooperating cases. We consider a square differentially-heated cavity filled with nongray air-CO2 or air-H2O mixtures. The governing equations are solved by a finite-difference method. The radiative sources are evaluated by the discrete ordinates method associated to the SLW spectral model. Results obtained for two average concentrations of CO2 and H2O (10% and 25%) show that radiation influences the temperature and concentration fields by creating oblique stratifications. The Nusselt numbers are decreased, whereas the Sherwood numbers are only slightly reduced. These effects are accentuated in air-H2O mixtures
Effect of horizontal walls emissivity on coupled double diffusive convection and non gray-gas radiation of air-H2O mixture in a cooperating case
(IEEE, 2015) Cherifi, M.; Benbrik, Abderahmane; Laouar-Meftah, Siham; Lemonnier, D.
Etude du phénomène d'évaporation de GNL dans les bacs de stockage aérien
(HAL, 2007) Hariti, Rafika; Benbrik, Abderahmane; Lemonnier, Denis; Khaldi, Khaled
Nous cherchons à prédire le taux d’évaporation du gaz naturel liquéfié (GNL) dans les bacs de stockage aérien en fonction des infiltrations thermiques à travers les parois. Nous montrons qu’un modèle réduit, fondé sur l’hypothèse (i) que la couche supérieure de vapeur est stablement stratifiée, (ii) que le transfert thermique se fait essentiellement par conduction dans le fluide comme dans les structures et (iii) tenant compte des échanges radiatifs internes, permet de prédire des profils de température en bon accord avec les relevés expérimentaux sur site. Ce modèle permet des évaluations fiables du taux d’évaporation global dans des cas correspondant aux conditions réelles d’exploitation
Flow simulation and performance analysis of a drilling turbine
(the Academic Publication Council of Kuwait University, 2020) Sahnoune, Khaled; Benbrik, Abderahmane; Mansour, Ahmed Saeed Mohamed; Rekik, Oussama
Turbodrills are axial hydraulic turbines which are used in drilling hydrocarbons in extreme conditions, possessing advantages over other drilling techniques with their high speed of rotation, and higher operating torques. In The present work, a numerical simulation of a Newtonian Drilling Mud flow was carried out through one stage of this turbine that has a stator and a rotor. The steady state mixing plane model was used for the simulations to take the rotation of the rotor into account besides the spatially averaged property fluxes of the flow. The turbulence K-ε model was used to consider the turbulence effects. Key performance parameters are calculated as a function of rotation speed and they are validated against the experimental data of the same model geometry in real operating conditions, a good agreement have been found between manufacturer power and torque data, and our simulation results for the same variables. Various flow fields are presented such as velocity and pressure, which had a great influence on the performance of the studied turbine. This will lead to choose the best parameters configuration of an optimal field operation.
Gas radiation effects on opposing double-diffusive convection in a non-gray air–H2O mixture
(Elsevier, 2014) Laouar-Meftah, Siham; Cherifi, Mohamed; Lemonnier, Denis; Benbrik, Abderahmane
We studied numerically the effects of gas radiation on double-diffusive convection in a square enclosure filled with a non-gray air–H2O mixture at different concentrations. Uniform temperatures and concentrations are imposed along the two vertical side walls of the enclosure so as to induce opposing thermal and mass buoyancy forces within the fluid. In this work, the radiative aspect of the problem is treated by the discrete ordinate method (to solve the radiative transfer equation) and the SLW spectral model (to account for the radiative properties of the non-gray mixture). Gas absorption varies with the local concentration of H2O, which induces a strong direct coupling between the concentration and thermal fields that otherwise would not exist. Numerical results show that radiative effects on the characteristics of streamline, temperature and concentration fields are important, and depend on the nature of the flow regime (thermal at 5% H2O, transitional at 10% and mass at 25%). The total heat transfer is reduced whatever the flow regime and the mass transfer is also affected, outside the thermal flow
Interaction between double diffusive natural convection and radiation in a square enclosure with partially active vertical wall
(Digital library International Centre for Heat and Mass Transfer Digital Library, 2016) Cherifi, M.; Benbrik, Abderahmane; Lemonnier, Denis; Meftah, Laouar
A numerical study is performed to investigate the effect of surface and volume radiation on the double diffusive natural convection in a square enclosure with a partially active side wall subjected to opposite and horizontal temperature and concentration gradients. The partially active vertical left side wall and fully active vertical right side wall of the enclosure are maintained at two different but uniform temperatures and concentrations. The remaining boundaries are impermeable and thermally insulated. These walls are assumed to be opaque, diffuse and grey and the working fluid is considered as grey, absorbing, not scattering and emitting thermal radiation. The governing differential equations are solved by a finite-volume method and the SIMPLE algorithm was adopted to solve the pressure–velocity coupling. The discrete ordinates method (DOM) is used to solve the radiative transfer equation within the fluid. Three different relative positions of the active part of the left wall were considered: this parameter has a significant effect on heat and mass transfer as well as the flow structure. The effects of some other influencing parameters have been investigated too, such as the fluid opacity and the mass to thermal buoyancy ratio
Interaction of radiation with double-diffusive natural convection in a three-dimensional cubic cavity filled with a non-gray gas mixture in cooperating cases
(taylor and francis, 2016) Cherifi, M.; Laouar-Meftah, Siham; Benbrik, Abderahmane; Lemonnier, D.; Saury, D.
Laminar natural convection flow in cylindrical cavity application to the storage of LNG
(Elsevier, 2010) Khelifi-Touhami, M. S.; Benbrik, Abderahmane; Lemonnier, D.; Blay, D.
The numerical simulation of laminar natural convection in a vertical cylindrical cavity is proposed. The cavity is insulated at the bottom, laterally heated at a uniform heat flux and cooled by a non uniform evaporative heat flux at the top surface obeying the Hashemi–Wesson's law. The equations of mass conservation, momentum and energy are resolved with finite-volume method in fully implicit form. The influence of the characteristic parameters (103≤Ra≤105, Pr=2, 1/3≤Al≤1) on the thermal and dynamic behavior at steady state is analysed and discussed. In particular, the study describes the solutions at Ra=105 and Pr=2 for various aspect ratios. The evaporative heat flux is computed for all the parameters and it is found that its maximum is localized near the lateral wall whereas its minimum is at the free surface center
Modeling of radiative heat transfer of a real gas in 2D enclosure
(2014) Cherifi, Mohammed; Laouar-Meftah, Siham; Benbrik, Abderahmane
A two-dimensional radiation code based on the discrete ordinates method (DOM) coupled with spectral line-based weighted sum of grey gases (SLW) model for radiative heat transfer in non-grey absorbing–emitting media for use in conjunction with a computational fluid dynamics (CFD ) code was developed. The code was applied to four different kinds of participating media: two homogeneous and isothermal and two non-homogeneous and non- isothermal cases with a single participating gas (CO 2 or H 2 O). Predictive accuracy of the code is compared with the available results in the literature. Comp arisons reveal that the discrete or dinates method (DOM) coupled with SLW model provides accurate solutions for ra diative heat fluxes and source terms and can be used with confidence in conjunction with CFD codes
Modelisation of turbulent natural convection in rectangular cavity filled with methane
(2011) Benbrik, Abderahmane; Khelifi Touhami, M. S.; Sahnoune, K.; Laouar-Meftah, Siham
Non-gray gas radiation effect on mixed convection in lid driven square cavity
(AIP Conference Proceedings, 2016) Cherifi, Mohammed; Benbrik, Abderahmane; Laouar-Meftah, Siham; Lemonnier, Denis
A numerical study is performed to investigate the effect of non-gray radiation on mixed convection in a vertical two sided lid driven square cavity filled with air-H2O-CO2 gas mixture. The vertical moving walls of the enclosure are maintained at two different but uniform temperatures. The horizontal walls are thermally insulated and considered as adiabatic walls. The governing differential equations are solved by a finite-volume method and the SIMPLE algorithm was adopted to solve the pressure–velocity coupling. The radiative transfer equation (RTE) is solved by the discrete ordinates method (DOM). The spectral line weighted sum of gray gases model (SLW) is used to account for non-gray radiation properties. Simulations are performed in configurations where thermal and shear forces induce cooperating buoyancy forces. Streamlines, isotherms, and Nusselt number are analyzed for three different values of Richardson’s number (from 0.1 to 10) and by considering three different medium (transparent medium, gray medium using the Planck mean absorption coefficient, and non-gray medium assumption)
Numerical study of double-diffusion convection coupled to radiation in a square cavity filled with a participating grey gas
(2008) Mezrhab, A.; Lemonnier, D.; Meftah, S.; Benbrik, Abderahmane
This paper presents numerical solutions for the coupled radiation and natural convection heat transfer by double diffusion in a square cavity. The governing differential equations are solved by a finite-volume method, by adopting the SIMPLER algorithm for pressure–velocity coupling. The discrete ordinate method is used in modelling the radiative transfer equation. The working fluid is considered as grey, absorbing, emitting and not scattering. The walls of the enclosure are assumed to be opaque, diffuse and grey. A parametric study is performed to illustrate the influence of the Rayleigh number, the buoyancy number, the Lewis number and the optical thickness on the flow structure, the heat and mass transfer. The results obtained can be used as benchmark solutions for the validation of the codes treating the combined natural convection heat transfer by double diffusion and radiation