The breaking of nonlinear internal waves (NLIWs) in internal swash zones (ISZs), regions which develop along sloping oceanic boundaries through the action of periodically incident internal waves (IWs), is explored through high resolution numerical simulations using a spectral-element-method-based incompressible flow solver. The periodic shoaling and breaking of IWs in shallow environments, like continental shelves or slopes, has a direct impact on the internal thermal equilibrium and biogeochemistry of the water column. This dissertation discusses different aspects of the high-accuracy/resolution simulation of a model internal swash zone. The first part of this work focuses on the design, implementation and validation of boundary conditions for the robust generation and simulation of periodic finite-amplitude internal waves in a quasi two-layer continuous stratification. To overcome the shortcomings of the commonly-used Eulerian approach in generating robust high-amplitude periodic deep-water internal waves in a nonlinear stratification, an Euler-Lagrange approach is developed and implemented. Central to this approach is to take into account the wave-induced (isopycnal) displacement of the pycnocline in both the vertical and horizontal directions. Application of the optimized Euler-Lagrange approach, in a sharp two-layer stratification representative of seasonally stratified lakes, is demonstrated to generate robust finite-amplitude periodically-forced internal waves for a range of Froude numbers (i.e. wave amplitudes). The resolution required to achieve a prescribed level of accuracy in satisfying the on-slope zero-flux boundary condition for the density field along the linearly sloping boundary is also investigated. In the next part of this dissertation, the two-dimensional study of the interaction of finite-amplitude incident periodic waves with a linearly sloping boundary over multiple wave periods is explored for different values of wavelengths, Froude numbers and stratification choices. The importance of the choice of the sea-bed boundary condition (no-slip/free-slip) in the breaking mechanisms is highlighted. The effects of the different governing parameters on the wave breaking are detailed through the description of the mechanisms at play. The similarities in the dissipation rate and the kinetic energy across the different cases is described. A strong emphasize is placed on the importance of studying multiple breaking events to understand the global dynamic of an ISZ. The presence of a transient regime followed by a following steady-state like regime is revealed. Finally, in the last chapter of this dissertation, the high resolution simulations of a three-dimensional model ISZ are presented with a particular focus on the generation and evolution of turbulent boluses propagating up-slope through multiple breaking events. The results are compared and contrasted to their two-dimensional counter part. The study includes the determination of the transverse width of the domain as well as a study of the effects of changing the time of noise insertion in the simulation.