A stochastic method in simulating particles transport and deposition in wall-bounded turbulent flow

摘要

Aiming at the coolant leakage monitor in the containment of a nuclear power plant, a quick numerical method of simulating radioactive aerosols transport and deposition in the near-wall region is studied in this paper. A stochastic method basing on turbulence statistics is proposed to generate anisotropic turbulent fluctuations and track particles motion separately. The model of interactions between airflow and particles is established, and the algorithm of air velocity generation is developed and validated by comparison with DNS statistical results. The longtime transport and diffusion of aerosols in a rectangle channel are simulated in this paper, particles trajectories and instantaneous distribution can be obtained. Due to the nonuniform distribution of velocity fluctuations in wall-bounded flow, the phenomenon of turbophoresis is found from the evolution of particles concentration distribution. Five kinds of particle diameters ranged from 0.1 to 10 mu m and three particle densities of 500, 1000, 2500 kg/m(3) are considered to compare the deposition characteristics, accordingly, the dimensionless particle relaxation time (tau(+)) is ranged from 10(-6) to 10(-1). According to statistical analysis, the dimensionless deposition velocities (V-d(+)) versus tau(+) are obtained and well agree with the Wood's predictions basically within the error scope of +/- 30%. It is proved that the method employed in this paper is accurate in tracking particles motion in wall-bounded flow fluids. (C) 2018 Elsevier Ltd. All rights reserved.