Nano-particle deposition in axisymmetric annular pipes with thread

Abstract

The transport and deposition of nano-particles in annular threaded pipes under laminar flow conditions were studied and compared with smooth annular pipes. A 2-D axisymmetric model was used for fluid flow simulation and the Lagrangian particle tracking method was used for particle simulating. The effects of thread size and nano-particle diameters in the range of 5 to 200 nm were studied for different annular pipe lengths. For the smooth annular pipe, the Brownian excitation is the dominant force for particle deposition in the range of nanoparticles without any external force. The simulation results showed enhancement of particle deposition for pipes with threads especially for larger particles due to their inertia effects. However, for particles smaller than 40 nm, the addition of threads had little influence on increasing the deposition efficiency. The maximum increase in the particle deposition was found for a thread length of 3 mm where the hydraulic diameter and height of the threads are equal to 1 mm. The increase was 5.3 and 33.9% for 10 and 100 nm particles, respectively, compared with a smooth annular pipe with the same length. For deposition of large size nanoparticles, the study also showed that the effect of thread decreases as the annular pipe length increases.