Aeolian erosion of storage piles yards: contribution of the surrounding areas
Résumé
Dust emissions from stockpiles surfaces are often estimated applying mathematical models such as the widely used model proposed by the USEPA. It employs specific emission factors, which are based on the fluid flow patterns over the near surface. But, some of the emitted dust particles settle downstream the pile and can usually be re-emitted which creates a secondary source. The emission from the ground surface around a pile is actually not accounted for by the USEPA model but the method, based on the wind exposure and a reconstruction from different sources defined by the same wind exposure, is relevant. This work aims to quantify the contribution of dust re-emission from the areas surrounding the
piles in the total emission of an open storage yard. Three angles of incidence of the incoming wind flow are investigated (30◦, 60◦ and 90◦). Results of friction velocity from numerical modelling of fluid dynamics were used in the USEPA model to determine dust emission. It was found that as the wind velocity increases, the contribution of particles re-emission from the ground area around the pile in the total emission also increases. The dust emission from the pile surface is higher for piles oriented 30◦ to the wind direction. On the other hand, considering the ground area around the pile, the 60◦ configuration is responsible for higher emission rates (up to 67 %). The global emissions assumed a minimum value for the piles
oriented perpendicular to the wind direction for all wind velocity investigated.