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

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.