A model for the movement of large solids in small sewers

An extensive series of experiments has been carried out to investigate the movement mechanisms and behaviour of large solids in small sewers. This paper describes the development, calibration and verification of a model (SOLID) based on data obtained from the experimental rig. It is used to predict solid movement with respect to 'limiting solid transport distance'. Key model parameters are the coefficients of static and dynamic friction, the shape factor of amorphous solids and the flow bypass coefficient. The model is shown to successfully represent the movement of a large solid down a small pipe, where the solid is moving as a sliding, leaking dam, particularly the first 'hop'. Limitations of the model include a limited facility to well represent multiple hops and the need for closely spaced computational nodes leading to small time steps, and long run times.