Numerical Study on the Microflow Mechanism of Heat Transfer Enhancement in Nanofluids

A numerical study on nanofluids turbulent flow in a horizontal tube was conducted. The turbulent flow characteristics of nanofluids is revealed by investigating any differences between three models (Eulerian-Eulerian, Euler-Lagrange, and large eddy simulation (LES)-Lagrange) to explore the mechanism of heat transfer enhancement in nanofluids from the microflow aspect. The results indicated that the velocity slip between phases, growth of fluctuating velocity, increase of small-scale vortexes, and migration effect of nanoparticles may impose an important influence on heat transfer behavior of nanofluids. Therefore, the variation in fluid flow characteristics becomes the determining factor of pressure loss increment and heat transfer enhancement in nanofluids.