Prediction of critical deposition velocity in particle-laden pipe flows

A novel empirical correlation for predicting the critical deposition velocity in particle-laden turbulent pipe flows is developed from particle resuspension data, and is further shown to be applicable to the prediction of the onset of deposition from particle sedimentation data. The present study further examines particle deposition in multiphase turbulent pipe flows utilising direct numerical and large eddy simulation of the continuous phase in conjunction with Lagrangian particle tracking. A four-way coupled technique is used to investigate the onset of particle deposition across a wide range of particle Stokes numbers ([[EQUATION]] to [[EQUATION]]), and critical particle deposition velocities generated from simulations are compared to those predicted by the empirical correlation. The concentration of particles producing dune-like structures and beds in the lower wall region of pipe flows is utilised to develop a method for forecasting the critical deposition velocity from the simulations. The results indicate that at high Stokes numbers, the particle dispersion function and mean vertical particle displacement values fall quickly, and the formation of beds is observed. However, at lower Stokes numbers thinner dune-like structures are formed on the lower pipe wall. Using a volume-coverage percentage in the near-wall region of the lower half of the pipe as an identifier to define of the onset of deposition provides good agreement with the empirical correlation for prediction of the critical deposition velocity.