Browsing by Author "Nehaoua, N."

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    Adsorption and dissociation of H2S on the anatase TiO2 (100) surface: DFT + U study
    (Iop science, 2018) Nehaoua, N.; Belkada, R.; Tala-Ighil, Razika
    This paper discusses the adsorption and dissociation of the hydrogen sulfide (H2S) molecule on the titanium dioxide surface. They were studied by density function theory (DFT). The GGA + U approach was used to analyze the adsorption behavior of the H2S molecule on the TiO2 anatase (100) surface. The results presented include adsorption energies, structural and electronic properties, charge transfer and work function. Different adsorption configurations are considered with coordination of H2S at the surface (Ti5c, (Ti5c)2, O2c and O3c sites). The calculated adsorption energies are -0.31, -0.28, -1.14 and -5.66 eV. The most favorable adsorption sites lead to the dissociation of H2S into HS and H, where the S atom of HS binds to Ti5c or O2c atoms, leaving a dissociated H atom bonded to another O2c site. Analysis of Bader's charges reveals a significant charge transfer between the molecule and the surface of the TiO2 anatase. The adsorption process reduces the work function and bandgap of the system, which improves the photocatalytic properties of TiO2
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    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.