A comprehensive review on mixed convection of nanofluids in various shapes of enclosures

In the current study, heat transfer performances and flow characteristics of alumina–copper/water (Al2O3–Cu/H2O) hybrid nanofluid over a stretching cylinder are explored under the influence of Lorentz magnetic forces and thermal radiation. The Roseland’s flux model is employed for the impact of thermal radiations. The governing flow problem comprises of nonlinear ordinary differential equations, which are transformed into nondimensional form via suitable similarity transforms, Boussinesq and boundary layer approximations. Results of heat and fluid flow as well as convective heat transfer coefficient and skin friction coefficient under influence of embedding parameters are displayed and discussed through tables and graphs. To check its heat transfer performance, a comparison of hybrid nanofluid with base fluid and single material nanofluids is also made and found that hybrid nanofluids are more effective in heat transfer than conventional fluids or single nanoparticles-based nanofluids.

Heat transfer enhancement in hydromagnetic alumina–copper/water hybrid nanofluid flow over a stretching cylinder

Hybrid nanofluid flow and heat transfer over backward and forward steps: A review

3D mixed convection MHD flow of GO-MoS2 hybrid nanoparticles in H2O–(CH2OH)2 hybrid base fluid under the effect of H2 bond

A rigorous mathematical approach is presented to understand the transparent impacts of Buongiorno nanofluid model on the rate of heat and mass transfer in different fluid flow geometries. Unlike the numerical simulations available in the recent open literature, the currently derived formulas enable us to analytically explain why heat and mass transfer should be enhanced or reduced by the frequently used Buongiorno nanofluid model accounting for the Brownian motion and thermophoresis effects. Two distinct boundary constraints are taken into account usually employed in this model by the active researchers working in this field. Hence, both the constant wall mass as well as the zero net particle mass flux on the wall are studied analytically. Initially, the obtained results are tested on the well-documented Crane’s linearly stretching sheet solution with perfect agreement and accuracy. Then, the solutions are validated on some published results. From the asymptotic formulas not only the special quantitative values but also the general trends of heat and mass transfer can be estimated accurately.

On the transparent effects of Buongiorno nanofluid model on heat and mass transfer

The present paper investigates numerically the effect of an external magnetic field on heat transfer and entropy generation of Ag–MgO (50:50 vol%)/water hybrid nanofluid flow in a partially heated irregular ventilated cavity. A finite-volume FORTRAN code has been written to solve the governing partial differential equations. New empirical correlations specifically dedicated to predict the dynamic viscosity and the thermal conductivity of the considered hybrid nanofluid were employed. After validation of model, the analysis has been done for a wide range of Reynolds number (10 ≼ Re ≼ 600), Hartmann number (0 ≼ Ha ≼ 80) and total nanoparticle volume fraction (0 ≼ φ ≼ 0.02). The results are presented in terms of streamlines, isotherms and isentropic lines as well as the average Nusselt number (Num), the average entropy generation (Sgen,m) and the Bejan number (Beavg). The criterion ξ = Sgen,m/Num is adopted to discuss the thermal performances of the system. The results reveal that the intensification of the magnetic field tends to attenuate the heat transfer convection and to reduce the thickness of the thermal boundary layer, close to the active walls. Globally, adding nanoparticles to the base fluid improves the heat transfer but increases the total entropy generation.

Second law analysis of MHD mixed convection heat transfer in a vented irregular cavity filled with Ag–MgO/water hybrid nanofluid

The present paper reports a numerical investigation of steady and laminar mixed convection flow within an irregular ventilated enclosure, crossed by Cu–Water nanofluid. The bottom wall is maintained at a constant and uniform temperature, whereas the top and the vertical walls are adiabatic. The inclined wall as well as the nanofluid at the entrance is kept at a lower constant temperature. The governing coupled equations are resolved by the means of the finite volume technique. The computations are performed using a homemade computer code, which was successfully validated, after comparison of our results with pervious numerical and experimental works. Empirical relations to predict the nanofluid’s effective thermal conductivity and viscosity were employed. The results are analyzed through dynamic and thermal fields with a particular attention to the Nusselt number evaluated along the active wall. The results reveal that the flow structure is more sensitive to both Richardson and Reynolds numbers variations. Moreover, heat transfer is enhanced by the increase in the nanoparticles volume fraction, Richardson and Reynolds numbers and by the decrease in the nanoparticles diameter. Useful correlations predicting the heat transfer rate as a function of nanoparticles volume fraction and diameter as well as the Richardson number are proposed.

Numerical Mixed Convection Heat Transfer Analysis in a Ventilated Irregular Enclosure Crossed by Cu–Water Nanofluid

Numerical study of the flow in a square cavity filled with Carbopol-TiO2 nanofluid

In the present work, we investigate numerically the fluid flow and heat transfer inside an entrapped cavity, which has an isosceles triangular cross-section and is filled with TiO2–water nanofluid. The base wall is maintained at high constant temperature, while the two other sides are kept a lower constant temperature. The length of the cavity is large enough to assume that the flow is two-dimensional. The governing equations are discretized by the finite volume method and solved numerically via the SIMPLER algorithm. In the present work, we investigate the effect of some parameters including the Rayleigh number, the solid volume fraction, the cavity aspect ratio and the inclination angle on both the thermal performance and the flow structure. The obtained results show that the thermal performance of the cavity and the flow structure are most sensitive to Rayleigh number and solid volume fraction. On the other hand, the aspect ratio of the cavity and its inclination also affect considerably the heat transfer and fluid flow pattern. We notice the occurrence of a pitchfork bifurcation phenomenon, which is a function of both Rayleigh number and cavity aspect ratio. Our results provide information that may be useful for design optimization as well as for thermal performance enhancement of energy systems such as solar water heaters.

Seif-Eddine Ouyahia

Papers

Second law analysis of MHD mixed convection heat transfer in a vented irregular cavity filled with Ag–MgO/water hybrid nanofluid

Numerical Mixed Convection Heat Transfer Analysis in a Ventilated Irregular Enclosure Crossed by Cu–Water Nanofluid

Numerical study of the flow in a square cavity filled with Carbopol-TiO2 nanofluid

Numerical Study of the Hydrodynamic and Thermal Proprieties of Titanium Dioxide Nanofluids Trapped in a Triangular Geometry

Effect of backward facing step shape on 3D mixed convection of Bingham fluid