Numerical investigation on particle deposition enhancement in duct air flow by ribbed wall

• Particle deposition velocities on smooth and ribbed walls are numerically investigated.
• Particle deposition is significantly enhanced by surface ribs especially for small particles.
• Turbulent eddies induced by the ribs play important roles on particle deposition enhancement.
• Pressure drop-weighted deposition enhancement is evaluated for different particle sizes.

This paper studied the particle deposition in turbulent duct air flows with smooth and ribbed walls numerically. The RSM model with turbulent fluctuation correction and Lagrangian track method were adopted to investigate the particle deposition enhancement by ribbed surface. The air flow velocity profiles for both smooth and ribbed-ducts as well as particle deposition velocity on smooth wall obtained in the present simulation were validated by agreeing well with the previous related study data. Particle deposition is significantly enhanced by surface ribs, especially in turbulent diffusion and eddy diffusion-impaction regimes. It is found that the captures of turbulent eddies induced by ribs and entrainments of large turbulent kinetic energy (T.K.E.) to the wall are the main mechanism for deposition enhancement of small particles. Moreover, pressure drop-weighted efficiency ratio of particle deposition enhancement for ribbed surface is evaluated in this study. The efficiency ratio for ribbed surface can reach more than 100 for particle sizes 0.2–3 μm but only about 2–3 for particle sizes 20–50 μm. This study shows that the repeated ribs on the surface could be an effective and efficient choice for particle deposition enhancement, especially for micron-meter particles.