Chin.J.Chem.Eng. ›› 2012, Vol. 20 ›› Issue (4): 679-685.

• FLUID FLOW AND TRANSPORT PHENOMENA • Previous Articles     Next Articles

Nanoparticle migration in a fully developed turbulent pipe flow considering the particle coagulation

LIN Jianzhong1,2; LIU Song2; CHAN Tatleung3   

  • Received:2011-04-05 Revised:2011-11-12 Online:2011-11-12 Published:2012-08-28

考虑颗粒凝并情况下充分发展圆管湍流场中的纳米颗粒的迁移

林建忠1,2, 刘淞2, 陈达良3   

  1. 1 China Jiliang University, Hangzhou 310018, China 2 State Key Laboratory of Fluid Power Transmission and Control, Zhejiang University, Hangzhou 310027, China 3 Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

Abstract: Numerical simulations of nanoparticle migration in a fully developed turbulent pipe flow are performed. The evolution of particle number concentration, total particle mass, polydispersity, particle diameter and geometric standard deviation is obtained by using a moment method to approximate the particle general dynamic equation. The effects of Schmidt number and Damköhler number on the evolution of the particle parameters are analyzed. The results show that nanoparticles move to the pipe center. The particle number concentration and total particle mass are distributed non-uniformly along the radial direction. In an initially monodisperse particle field, the particle clusters with various sizes will be produced because of coagulation. As time progresses, the particle cluster diameter grows from an initial value at different rates depending on the radial position. The largest particle clusters are found in the pipe center. The particle cluster number concentration and total particle mass decrease with the increase of Schmidt number in the region near the pipe center, and the particles with lower Schmidt number are of many dif-ferent sizes, i.e. more polydispersity. The particle cluster diameter and geometric standard deviation increase with the increase of Damköhler number at the same radial position. The migration properties for nano-sized particles are different from that for micro-sized particles.

Key words: nanoparticle, coagulation, turbulent, pipe flow

摘要: Numerical simulations of nanoparticle migration in a fully developed turbulent pipe flow are performed. The evolution of particle number concentration, total particle mass, polydispersity, particle diameter and geometric standard deviation is obtained by using a moment method to approximate the particle general dynamic equation. The effects of Schmidt number and Damköhler number on the evolution of the particle parameters are analyzed. The results show that nanoparticles move to the pipe center. The particle number concentration and total particle mass are distributed non-uniformly along the radial direction. In an initially monodisperse particle field, the particle clusters with various sizes will be produced because of coagulation. As time progresses, the particle cluster diameter grows from an initial value at different rates depending on the radial position. The largest particle clusters are found in the pipe center. The particle cluster number concentration and total particle mass decrease with the increase of Schmidt number in the region near the pipe center, and the particles with lower Schmidt number are of many dif-ferent sizes, i.e. more polydispersity. The particle cluster diameter and geometric standard deviation increase with the increase of Damköhler number at the same radial position. The migration properties for nano-sized particles are different from that for micro-sized particles.

关键词: nanoparticle, coagulation, turbulent, pipe flow