Department of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran.
Faculty of Chemical Engineering, Malek Ashtar University of Technology, Tehran, Iran.
In this study, eect of dierent slip mechanisms that can produce a slip velocity between nanoparticles and base fluid in a nano fluid flow eld has been investigated numerically. A two-phase Euler-Lagrange approach was applied to simulate heat transfer characteristics of dierent nanoparticles in a straight tube under laminar flow condition. Effect of dierent mechanisms such as thermophoresis, Brownian diusion, and Saman lift force on convective heat transfer was investigated and discussed. It is noticed that only Brownian diusion and thermophoresis are important slip mechanisms in nano fluids. In dierent nano fluids, eect of Brownian diusion and thermophoresis on convective heat transfer is dierent. While eect of Brownian diusion is more important in CuO-water nano fluid, thermophoresis is the main slip mechanism in Al2O3-water nano fluid.