Low pressure injection makes a significant contribution to NOX and CO2 emission reduction e.g. by SCR applications or water injection. The cause-and-effect chain between injector nozzle design and atomization of the liquid requires a transition from parameter based product design to knowledge based product design which is a significant innovation jump in industry. A high-fidelity 3D flow simulation method for the comprehensive simulation of the atomization, including in- and near-nozzle flow field and direct resolution of primary break-up process is proposed. The directly resolved primary ligaments are coupled to a particle-based spray simulation method for the far-nozzle field. This seamless simulation of near- and far-nozzle effects will be applied to understand the cause-and-effect chain of the entire atomization process. The simulation method is validated by high-end measurement techniques. Based on the highly-resolved reference simulation results, transfer functions are derived that may be implemented in the industrial R&D-process and enable a fast daily design analysis and assessment of atomization performance. Since the transfer function has been develop based on high-fidelity reference simulation results a fast and at the same time accurate design tool is available which allows a significant reduction of turn-around times and costs. A tangible reduction of NOx and CO2 emissions is expected by the contribution of Delphi low pressure injectors. The seamless simulation of atomization by low-pressure injection devices is a completely new computational approach and an enabler for the understanding of the entire cause-and-effect chain. Therefore, a new field of simulation methods is launched, and an exceptionally high scientific impact may be expected on the comprehensive simulation of in-nozzle flow and atomization.