Transport of nanoparticles and coagulation is simulated with the combination of CFD in a circular bend The Taylor-expansion moment method (TEMOM) is employed to study dynamics of nanoparticles with Brownian motion, based on the flow field from numerical simulation A fully developed flow pattern in the present simulation is compared with previous numerical results for validating the model and computational code. It is found that for the simulated particulate flow system, the particle mass concentration, number concentration, particle polydispersity, mean particle diameter and geometric standard deviation over cross-section increase with time The distribution of particle mass concentration at different time is independent of the initial particle size More particles are concentrated at outer edge of the bend Coagulation plays more important role at initial stage than that in the subsequent period. The increase of Reynolds number and initial particle size leads to the increase of particle number concentration The particle polydispersity, mean particle diameter and geometric standard deviation increase with decreasing Reynolds number and initial particle size.