Particle deposition in turbulent square duct flows

Particle deposition in fully developed turbulent square duct flows is predicted using large eddy simulation for Reynolds numbers, based on the bulk flow velocity and duct width, equal to 250k, 83k and 10,320. A particle equation of motion, solved in conjunction with a Lagrangian particle tracking technique, and including Stokes drag, lift, buoyancy and gravitational forces is used to analyse the trajectory of 50, 100 and 500 μm particles. Results obtained for the fluid phase show good agreement with experimental data and the predictions of direct numerical simulations. Predictions for particles show that high-inertia particles (Stokes number, St > 12.38) tend to deposit close to the corners of the duct floor, while low-inertia particles ( St < 6.43) deposit near the floor centre. Particle deposition in the vertical direction is also found to increase with flow Reynolds number, whilst in the horizontal direction deposition increases with particle size and decreases with Reynolds number. Additionally, and in both the vertical and horizontal directions, the deposition profile, as quantified by the probability density function of deposited particle locations, is more variable for small particles when compared to larger ones, independent of the flow Reynolds number.