A Model of Silage Consolidation and Effluent Flow

Abstract A mathematical model of silage consolidation and effluent flow is presented. Silage is modelled as a porous deformable medium containing a fluid. Model predictions for silage settlement heights and effluent production are found to be in good agreement with those found in laboratory-scale experiments (6kg of grass silage) and with findings reported in the literature for full-size silos containing several hundred tonnes of silage. The model can provide a quantitative understanding of the processes involved in effluent production so that scientifically based solutions to problems, such as the effective use of absorbents, can be reached. The model has been used to assess the importance of dry-matter content and silo geometry in determining effluent production. The height/diameter ratio of a silo is predicted to have a significant effect on effluent production. Increasing the height/diameter ratio is predicted to prolong the time from initial drainage to the peak flow of effluent.