The steady normalized centerline-velocity distribution proximal to an orifice has been used in quantifying valvular regurgitation with color Doppler (CD). However, the presence of pulsitility and constraining walls in a viscous flowfield may influence the centerline flow characteristics. This study utilized computational fluid dynamic (CFD) models of the flow region proximal to an axisymmetric orifice to investigate the combined effects of adjacent wall influence and time dependence on the proximal flowfield. Steady state conditions and time waveforms for flowrate and pressure-gradient were used as input boundary conditions. Results of this study indicate that normalized centerline velocity distributions depend on adjacent wall orientation. However, for a specific wall orientation, the instantaneous, normalized, centerline-velocity distribution showed little deviation from steady state distributions. These results suggest that the steady state proximal centerline velocity distribution is a good approximation the pulsatile centerline distribution for a specific time.