Various methods for approximating the non-linear advection terms in a high resolution tidal model with complex coastal boundaries have been implemented and tested. The model, driven by the dominant M2 tidal component at the open boundaries, has been applied to a model domain with 100 meter grid resolution for the Tjeldsundet channel in northern Norway. Overtides, intensivated jets and eddy structures appear in the current fields of the full non-linear simulations. How these flow features depend on the way the friction terms are calculated and the way the non-linear advection terms are calculated in a zone near the coastal boundaries, are discussed. Some comparison with field measurements have also been made.