Effects of chemical reactions on iterative methods for implicit time stepping

We compare the performance of the fully coupled Newton–Raphson method with the sequential iteration approach (SIA) for solving the implicit time stepping equations of reactive transport modeling. We formulate the implicit time stepping equations for a demonstration model that incorporates homogeneous equilibrium reactions, i.e. carbonate hydrolysis, and a heterogeneous equilibrium reaction, i.e. the dissolution/precipitation of calcite. The demonstration model uses a coupled pair of mixing cells as a simplified form of transport. The effects of the homogeneous and heterogeneous reactions on the iterative methods are demonstrated.