The present computational study aims to examine the effectiveness of a downstream microjet fluidic injection (DMFI) scheme in altering the mixing characteristics of supersonic jets in an effort to reduce supersonic jet noise. DMFI scheme, based on our previous experimental study involves perpendicular injection into a supersonic cross flow using four equally spaced injection ports placed on an injection tube which extends downstream of a Mach number 1.5 nozzle. Results of the present numerical investigation indicate good agreement with the previous experimental results; further demonstrating the effectiveness of DMFI scheme in altering the stability characteristics of the shear layer and hence mixing enhancement. The findings suggest that for a constant momentum flux ratio, injection at various axial locations leads to different levels of shear layer penetration. It is shown that perpendicular fluidic injection near the location where local shock wave is expected to occur and subsequent merging of this shock wave with the upstream separation bow shock, modifies the shear layer considerably and results in improved mixing and shear layer spreading. The DMFI scheme shows augmentation of turbulence intensity levels in the vicinity of the nozzle, leading to reduction of downstream turbulence intensities, which consequently influences the noise radiation into the far field.