Isothermal CFD analysis was performed on axially opposed rows of jets mixing with crossflow in a rectangular duct. Laterally, the jets' centerlines were aligned with each other on the top and boltom walls. The focus of this study was to characterize the effects of orifice aspect ratio and jet-to-mainstream mass flow ratio on jet penetration and mixing. Orifice aspect ratios (LIW) of 4-to-l, 2-to-l, and l-to-l , along with circular holes, were parametrically analyzed. Likewise, jet-to-mainstream mass flow ratios (MR) of 2.0, 0.5, and 0.25 were systematically investigated. The jet-tomainstream momentum-flux ratio (1) was maintained at 36 for all cases, and the orifice spacing-to-duct height (StH) was varied until optimum mixing was attained for each configuration.The numerical results showed that orifice aspect ratio (and likewise orifice blockage) had little effect on jet penetration and mixing.