Publications Internationales
Permanent URI for this collectionhttps://dspace.univ-boumerdes.dz/handle/123456789/13
Browse
8 results
Search Results
Item Effects of different thermal conductivity models and Ψ sphericity on mixed convection for hybrid nanofluids(Elsevier, 2025) Moussi S.; Abdellahoum C.; Mataoui A.; Oztop H.F.This work focuses on the combined effects of different thermal conductivity formulas for hybrid nanoparticles and the sphericity of these nanoparticles on the thermal behavior of a laminar flow of hybrid nanofluids in mixed convection through a partially heated pipe. The governing equations are solved by the finite volume method and using a structured and non-uniform mesh. This method used allows the behavior of nanofluids, which are complex mixtures of base fluid and nanoparticles, to be modeled. Simulations can take into account aspects such as the Brownian motion of particles and interactions between particles and fluid, thus improving the understanding of heat transfer phenomena. A percentage selection was made for a wide range of copper (5 %, 10 %, 15 %, 25 %, 40 %, 50 %) and three nanoparticle volume fractions (ϕ = 0.5 %, 2 %, 5 %). It was found that the effect of Cu is notable in the upper part of the section, where free convection is dominant in the presence of forced convective heat transfer due to the flow. We can also say that the percentage of copper and aluminum in nanofluids is a variable parameter and adjusted according to the application. There is no single value, but rather a range of concentrations that allows the desired performance to be achieved. A comparison between the numerical results and the experimental measurements available in the literature is carried out in order to validate the chosen numerical procedure. The Brownian model is associated with higher thermal conductivity, which means a greater ability to transfer heat. The Maxwell and Hamilton models show heat transfer characteristics very close to each other, which makes them less efficient than the Brownian model. This observation is crucial for choosing the most suitable model for an application where efficient heat transfer is sought, indicating that the processes describing the motion of particles in the Brownian model are the most efficient for moving thermal energy. Moreover, there is an increase in the average coefficients hup and hlow as the volume fraction of the nanoparticles in the fluid increases, for all values of the shape factor n1 of the alumina oxide particles, which represents 90% of the total volume fraction ϕ.Furthermore, the sphericity of nanoparticles affects the thermal properties of nanofluids by altering the interaction between the particles and the base fluid, as well as the particle arrangement. More spherical particles tend to maintain greater fluidity, reducing friction and aggregation, which can improve the thermal conductivity and stability of the nanofluid. The increase in thermal conductivity, one of the key properties of nanofluids, is directly influenced by this morphologyItem Effect of turbulence models' choice on the aero-thermal flow numerical validations within a ribbed trailing edge geometry(Sage, 2019) Beniaiche, Ahmed; Nadir, Mahmoud; Mahfoudh, Cerdoun; Carcasci, Carlo; Facchini, BrunoItem Heat transfer related to a self-sustained oscillating plane jet flowing inside a rectangular cavity(IEEE, 2014) Iachachene, Farida; Matoui, A.; Halouane, YacineItem Turbulent heat transfer for impinging jet flowing inside a cylindrical hot cavity(Serbian Society of Heat Transfer Engineers, 2015) Halouane, Yacine; Mataoui, Amina; Iachachene, FaridaConvective heat transfer from an isothermal hot cylindrical cavity due to a turbulent round jet impingement is investigated numerically. Three-dimensional turbulent flow is considered in this work. The Reynolds stress second order turbulence model with wall standard treatment is used for the turbulence predictions the problem parameters are the jet exit Reynolds number, ranging from 2·104 to 105 and the normalized impinging distance to the cavity bottom and the jet exit Lf, ranging from 4 to 35. The computed flow patterns and isotherms for various combinations of these parameters are analyzed in order to understand the effect of the cavity confinement on the heat transfer phenomena. The flow in the cavity is divided into three parts, the area of free jet, and the area of the jet interaction with the reverse flow and the semi-quiescent flow in the region of the cavity bottom. The distribution of the local and mean Nusselt numbers along the cavity walls for above combinations of the flow parameters are detailed. Results are compared against to corresponding cases for impinging jet on a plate for the case of the bottom wall. The analysis reveals that the average Nusselt number increases considerably with the jet exit Reynolds number. Finally, it was found that the average Nusselt number at the stagnation point could be correlated by a relationship in the form Nu = f(Lf, Re)Item Heat transfer investigation in new cooling schemes of a stationary blade trailing edge(Elsevier, 2015) Beniaiche, A.; Ghenaiet, A.; Carcasci, C.; Facchini, B.Item Numerical investigations on heat transfer of self-sustained oscillation of a turbulent jet flow inside a cavity(American Society of Mechanical Engineers (ASME), 2015) Iachachene, Farida; Mataou, Amina; Halouane, YacineItem Numerical study of a thermodependent non-Newtonian fluid flow between vertical concentric cylinders(Elsevier, 2007) Zeraibi, Noureddine; Amoura, M.; Benzaou, A.; Gareche, MouradIn this paper, we present a numerical investigation of the thermal convection for a thermodependent non-Newtonian fluid in an annular space between two coaxial rotating cylinders. The rheological behaviour of the fluid can be expressed through the Ostwald-De-Waele power law: View the MathML sourceτ=Kγ˙n; all fluid properties except consistency index K are constant. K–T relation used is K = K0e−bT. The problem is studied when the heated inner cylinder is rotating around the common axis with constant angular velocity and the cooled outer cylinder is at the rest. The horizontal endplates are assumed adiabatic. The governing equations are solved using mixed finite elements method. The influence of the temperature on the structure of the dynamic and thermal fields is examinedItem Finite element study of mixed convection for non-Newtonian fluid between two coaxial rotating cylinders(2006) Amoura, Mourad; Zeraibi, Noureddine; Smati, A.; Gareche, MouradIn this work, we present a numerical simulation of the flow characteristics and the heat transfer mechanism of a non-Newtonian fluid in an annular space between two coaxial rotating cylinders. The Carreau stress–strain relation was adopted to model the rheological fluid behaviour. The problem is studied when the heated inner cylinder rotates around the common axis with constant angular velocity and the cooled outer cylinder is at the rest. The horizontal endplates are assumed adiabatic. The governing equations are solved using mixed finite elements method. The effects of the different parameters on the heat transfer and on the flow are examined. These parameters are the Reynolds (Re), the Grashof (Gr) and the Weissenberg numbers (We), and the flow index (n). The results of the natural, forced and mixed convections are presented and discussed. © 2006 Elsevier Ltd. All rights reserved