Three-dimensional modelling of coupled leachate and gas flow in bioreactor landfills

A three-dimensional two-phase flow model for leachate and gas transportation in bioreactor landfills has been developed based on OpenFOAM. Darcy's law and the van Genuchten soil-water retention curve model are incorporated into the governing equations for leachate and gas flow. A modified Picard iteration method is introduced to solve the model. The developed model is effectively verified by published results. A three-dimensional conceptual landfill cell with leachate recirculation well and gas collection well is simulated. The results show that leachate recirculation is beneficial for gas collection, and the effect of gas on leachate recirculation can be neglected if the gas collection well is working.