On the assessment of modeling combined convection heat transfer in nanofluids using dissipative particle dynamics

The effect of nanoparticles on mixed convection heat transfer mechanisms in a vertical lid-driven cavity using dissipative particle dynamics method is addressed. The effect of nanoparticle concentration on the random heat flux and the total heat flux is assessed via simulating the opposing buoyancy mechanism in a lid-driven cavity filled with Al₂O₃-water nanofluids. The study covered a wide range of nanoparticles volume fraction (1% ≤ φ ≤ 5%), and three Richardson numbers were considered, Ri = 0.1, 1, and 10. The results were verified via comparing the temperatures and the streamlines contours with the ones obtained using finite-volume method over the same range of Richardson number and nanoparticles concentration. The effect of the compressibility of the system for natural convection dominated flows has been noted in the results as a deviation from the finite-volume results. The results reveal that the enhancement in the convection heat transfer is directly connected to the nanoparticles concentration, though the effect of the convection mechanism is more dominant. Also, it is found that the role of Brownian motion in the vicinity of hot and cold walls are negligible, where the ratio of random heat flux to the total heat flux is below 5%. For low nanoparticle concentration the enhancement of the total heat transfer is disperse, however for high nanoparticle concentration it is more localized to certain region depending on the Richardson number.