This study introduces a specialized Computational Fluid Dynamics (CFD) tool implemented within the OpenFOAM framework (Weller et al., 1998) to comprehensively explore injection and mixing phenomena under high-pressure conditions. The developed density-based solver integrates advanced techniques, including a combination of double-flux method for multispecies transport, Riemann solvers, and a low-dissipation method, ensuring high temporal and spatial accuracy. The application focuses on the investigation of underexpanded jets, specifically in contexts involving shock-wave and hydrogen gas interactions. Employing Large Eddy Simulation (LES) turbulence modeling techniques, the novel code's performance is rigorously assessed. Quantitative and qualitative comparisons are made with existing data from the literature to validate the computational results. Subsequent to the initial code evaluation, the computational framework, coupled with LES modeling, is utilized to examine the impact of nozzle exit geometry and various nozzle pressure ratios on jet characteristics. In particular angular orifices as present in hollow comb injectors for direct injection will be analyzed. The findings offer valuable insights into the influence of nozzle parameters on turbulent mixture formation in underexpanded jets, providing essential information on the effects of injection pressure. This research contributes to the advancement of understanding and optimizing injection processes under high-pressure conditions, with potential applications in diverse fields such as shock-wave interactions and hydrogen gas utilization. Also, This research contributes to the advancement of understanding and optimizing injection processes under high-pressure conditions, which is of great interest due to the increase in hydrogen utilization in diverse fields as the transportation and energy sectors.