Numerical simulation of nanoparticles coagulation process in a Cu/water nanofluids turbulent pipe flow

Abstract

Numerical simulations of Cu/water nanofluid in a turbulent pipe flow are performed with considering the particle convection, diffusion, and coagulation. A general dynamic equation(GDE) of nanoparticles in a turbulent pipe flow has been derived with the Taylor Expansion Method of Moment (TEMOM) and the nanofluid flow in a horizontal circular tube has been simulated using the large eddy simulation (LES). The numerical results show the initial uniform distributions of particle volume concentration and size become non-uniform. The particle size increases with the development of coagulation process and the smaller diameter particles show more violent coagulation process inducing larger particle diameter growth rate . Because of the mixing of nanoparticles with short coagulation process and a paraboloid velocity distribution, the average size of particle at the tube center is smaller than that of near the wall.