Effects of nanoparticles dispersion on the mixed convection of a nanofluid in a skewed enclosure

摘要

A non-homogeneous model in which the nanoparticles have relative velocity compared to the based fluid is considered to study the convective heat transfer of a Cu-water nanofluid in a differentially heated skewed enclosure. The effect of nanoparticles size, volume fraction, Brownian diffusion and thermophoretic diffusion on the mixed convection is studied and compared with the result due to the homogeneous model. The theromphysical properties of the nanofluid is considered to depend on the temperature and nanoparticle volume fraction. A pressure correction based algorithm is used to solve the transport equations.The effects of the relevant parameter such as, the size of the nanoparticles(30nm⩽dp⩽100nm), temperature difference(1K⩽ΔT⩽10K)and bulk volume fraction of the nanoparticles(0⩽ϕb⩽0.05)on mixed convection of nanofluid studied by considering the skew angle to vary between30°and150°. The analysis shows that the nanoparticles distribution is nonuniform inside the enclosure and this non-uniformity increases with the rise of the temperature difference. The variation of the average Nusselt number and total entropy generation with the variation of the relevant parameter is analyzed for the thermodynamic optimization. The purpose of the present study is to analyze the effects of Brownian diffusion and thermophoresis of nanoparticles on the mixed convection of a Cu-water nanofluid. The results show that the Brownian diffusion and thermophoretic diffusion has relatively negligible effects on the mixed convection for the considered range of parameter values.