A fully coupled numerical model for two-phase flow with contaminant transport and biodegradation kinetics

A fully coupled numerical model is presented which describes biodegradation kinetics and NAPL-aqueous two-phase flow in porous media. The set of governing partial differential equations is split in two subsystems, the former one in terms of phase pressure and saturations, and the latter one in terms of contaminant concentration and bacterial population distribution. Non-linear saturation dependence in Brooks-Corey relative permeability functions and capillary pressure effects are incorporated in a mixed-hybrid finite element model. The non-linear degradation kinetics a la Monod is taken into account as a source term in the finite-volume discretization of the equation modelling contaminant transport. The global coupling is performed by using a nested block-iteration technique. A set of numerical experiments demonstrates the effectiveness of the method. Sensitivity analysis results are also presented.