In this paper, developing laminar forced convection flow of a water-Al 2 O 3 nanofluid in a circular tube, submitted to a constant and uniform heat flux at the wall, is numerically investigated.A single and two-phase model (discrete particles model) is employed with either constant or temperaturedependent properties. The investigation is accomplished for size particles equal to 100 nm. The maximum difference in the average heat transfer coefficient between single and two phase models results is about 11%.Convective heat transfer coefficient for nanofluids is greater than that of the base liquid. Heat transfer enhancement increases with the particle volume concentration, but it is accompanied by increasing wall shear stress values. Higher heat transfer coefficients and lower shear stresses are detected in the case of temperature dependents models. The heat transfer always improves, as Reynolds number increases, but it is accompanied by an increase of shear stress too.Moreover a comparison with data present in the literature is carried out.

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In this paper developing laminar forced convection flow of a water–γAl2O3 nanofluid in a circular tube submitted to a constant and uniform heat flux at the wall is numerically investigated. A single and two-phase model (discrete particles model) is employed with either constant or temperature-dependent properties. The investigation is accomplished for a size particles equal to 100 nm. Convective heat transfer coefficient for nanofluids is greater than that of the base liquid. Heat transfer enhancement is increasing with the particle volume concentration but it is accompanied by increasing wall shear stress values. The effect of Reynolds number is greater when properties depend on temperature and for higher concentrations.

Purpose The purpose of this paper is to determine thermal behaviour of wing fuel tank wall via heating by external heat sources. Design/methodology/approach A 3D finite element model of the structure has been created that takes into account convection, conduction and radiation effects. In addition, a 3D finite volume model of the air inside the leading edge is created. Through a computational fluid dynamics approach, the flow of air and thermal behaviour of the air is modelled. The structure and fluid model are coupled via a co-simulation engine to exchange heat flux and temperature. Different ventilation cases of the leading edge and their impact on the thermal behaviour of the tank wall (corresponding to the front spar) are investigated. Findings Results of 3D analysis illustrate good insight into the thermal behaviour of the tank wall. Furthermore, if regions exist in the leading edge that differs significantly from the overall thermal picture of the leading edge, these are visible in a 3D analysis. Finally, the models can be used to support a flammability analysis assessment. Practical implications Provided that the bleed pipe is located far enough from the spar and covered with sufficient thermal heat isolation, the composite leading edge structure will not reach extremely high temperatures. Originality/value These detailed simulations provide accurate results which can be used as reliable input for the fuel tank flammability analysis.