It is proposed to investigate the effects of continental shelf/slope, bottom topography and friction on the dynamical balance of western boundary currents with a semi-primitive equation model (SPEM). High-resolution idealized calculations will be conducted and the momentum, vorticity and energy balances in these simulations will be compared with observations from the Gulf Stream. Comparisons will include the lateral and vertical structure of the model boundary current, the strength of the recirculation, the location of the separation point and the eddy dynamics of the separated current.